Memoir on the Eremophilus and Astroblepus, two new Genera of the Order of Apodes. By M. De Humboldt . From Recueil d’Observations de Zoologie et d’Anatomie comparé, 1re livraison. Communicated by a correspondent. When we ascend the chain of the Andes to the height of 2600 toises (16661 [Formel] English feet) and upwards, great level plains and lakes of a considerable extent are seen. It is singular to observe, that, while the soil is still covered with a beautiful vegetation, the woods filled with quadrupeds, and the air with a great variety of birds, the water alone, the lakes and the rivers, are so little inhabited. The cause of this phænomenon relates, without doubt, to geological facts; it pertains to the grand mystery of the origin and migration of species. The considerable lakes which surround the city of Mexico, at the height of 1160 toises , nourish but two species of fish, of which one, the axalotl, belongs rather to the genera sirenus and proteus. M. Cuvier, to whom we brought this extraordinarily organized animal, unknown in Europe, is engaged with its anatomy, which he will shortly publish. In the kingdom of New Granada, in the beautiful valley of Bogota, about 1347 toises high, there also exist but two species, which the inhabitants of that country call capitan and guapucha. The one is an atherine, and the other a new genus of apodes, that I am about to describe in this memoir. The form of its tail and its anal fin distinguish it sufficiently from the genus trichiurus, which is also found in the fresh waters of South America. I have designed this non-descript fish at the place; and Messrs. Lacepede and Cuvier, who have willingly examined my descriptions, like me, consider it a new genus well characterized. I have named it eremophilus on accout of the solitude in which it lives at so great an elevation, and in waters which are inhabited by almost no other living being. The naturalists, who fear that new species of the same genus may be discovered in very different situations, may change the name of eremophilus into that of thrichomycterus, taken from the barbillons or whiskers attached to the nose of this fish. The French toise is about six feet four inches nine-tenths English. EREMOPHILUS. (See Plate VIII.) Apod. Character Genericus Essentialis. Corpus elongatum. Cirri maxillares 4, nasales semitubulosi 2. Pinna dorsalis et analis. Membrana branchiostega radiis 1—2. E. Mutisii. Corpore elongato, plumbeo, cærulescenti, maculis dædaleis olivaceis variegato; operculi branchiostegi; duplicatura spinuloso-serrata. The body of the captain of Bogota is long, and has some analogy with that of the eel. It is compressed, of a blueish gray colour, and spotted with olive green. These spots, the outline of which forms very striking sinuosities, assume in some individuals a yellowish tint. The head is little and flat. The mouth, situated at the extremity of the nose, is straight. The upper jaw projects over the under one: the first, very long and double, is furnished with six fleshy barbillons or whiskers, of which the two exterior are the longest. Two other barbillons, shorter and semi-tubulous, are placed on the nostrils. It has very little eyes, which are veiled by a semi-transparent membrane, like the gymnotes and lampreys. The extremity of its lips is furnished with little teeth resembling hairs. The tongue is very fleshy, but short. The operculum or uvula forms a very narrow branchial opening, and it is very difficult to distinguish its folds (lames). In the most part of the individuals which I have examined, it appears to me that the captain, similar to the cyclopterus dentex and a few other fishes, has but two radii or furrows, which are as if soldered the one on the other. The edge of the operculum or uvula is indented. The dorsal fin has eight radii, the pectoral six, that of the anus six, and that of the tail, which is round, twelve radii: it has no swim or air-bladder. The length of this fish is from 10 to 11 inches, and its body is covered with a mucus common to the greater part of the apodes. It inhabits the little river of Bogota, that forms the famous cataract of Tequendama. The captain is a very agreeable aliment, and so much the more precious, that without it the inhabitants of the capital of Santa Fé, in the time of Lent, would be reduced to the use of only salted sea-fish brought from a great distance. I have given this species the trivial name Mutisii in houour of the celebrated naturalist, whose rich collections are preserved in the great valley of Bogota. The little river of Palacé, near Popayan, nourishes another fish, which, by its mucosity and the position of its fins, has some relation with the eremophilus, but which ought also to constitute a new genus of apodes. The breadth of its head is greater than that of the body; its eyes placed on the upper part of the head, and turned so that the pupils are directed, like as in the uranoscopus mus, towards the surface of the water; the indenting of the first radii of the fins, the branchial membrane of four radii; the tongue; the want of barbillons or whiskers on the nostrils; and the dorsal fin, which approaches more to the head than the tail; sufficiently distinguish the pescado negro (black fish) of Popayan from the capitan of Santa Fé. I have given the name of astroblepus to this genus, in allusion to the extraordinary situation of its eyes. ASTROBLEPUS. (See Plate VIII.) Apod. Character Genericus Essentialis. Corpus plagioplateum. Membrana branchiostega radiis 4. Oculi verticales. Cirri 2 maxillares, nasales nulli. A. Grixalvii. Corpore ex olivaceo nigrescenti, capite subtruncato, radiis pinnarum exterioribus serratis. Corpus plagioplateum, oblongum, nudum, olivaceo-nigrescens, caudam versus angustatum, subcompressum. Caput obtusum, magnum, subtruncatum. Cirri 2, apice recurvi et sublati, ricto in labio superiori adnati. Maxilla labiata, labio superiori majori plicatili. Lingua nulla. Nares 2 magnæ, margine membranaceo. Oculi verticales, minuti. Operculum simplex, convexum, nudum. Membrana branchiostega radiis 4, ossiculo anteriori subserrato. Pinua pectoralis radiis 10. Pinna analis radiis 7. Pinna caudalis integra radiis 12; radiis duobus exterioribus (ut omnium pinnarum) extrorsum serratis. Longitudo 14 pollicaris. I have given this fish the specific name Grixalvii to perpetuate the memory of a respectable philosopher, Don Mariano Grixalva, who has disseminated at Popayan a taste for the physical sciences, which he himself cultivated with success. Mutisii and Grixalvii are doubtless very scientific names. Linnæus, to gratify his puerile vanity, introduced the custom of giving arbitrary unmeaning names of men to plants: Werner embraced the same unphilosophical system of pitiable ambition in baptizing minerals (some wits have asserted, indeed, that such is his attachment to water, that he actually performed the ceremony of sprinkling certain stones, giving them at the same time the favourite name of some of his followers): and M. Humboldt now transfers men’s names to the very opposite abodes of fire and water, in his volcanic fish! All the labours of these men have done much less to disseminate a taste for the natural sciences, than the introduction of such an absurd practice has effected in obstructing the advancement of real knowledge and true philosophy. Posterity, so far from venerating such names, will execrate the being, who, to conceal his real ignorance by the assumption of universal knowledge, could thus deliberately bury true science and much accurate knowledge under the ruins of a Babylonish jargon! Peace to the manes of Lavoisier: although he himself made no real discoveries, yet the philosophical use which he made of those of the English and other philosophers will not speedily be forgotten by succeeding generations.—Translator. The pescado negro, so much eaten at Popayan, is found but in that part of the river Cauca which is most contiguous to the city. The physical cause of this phænomenon is sufficiently striking. From the volcano of Purasé descends a rivulet impregnated with sulphuric acid, that the inhabitants call Rio Vinagre (Vinegar River); it is known by the beautiful cascade which it forms at the foot of the volcano. From the point where the waters of Vinegar River unite with those of Cauca until four leagues lower down the latter is without fish, although in the upper part they are plentiful enough. The small quantities of acid that might escape our chemical analysis are often sufficiently great to injure the organization of fishes. Abbildungen