350 



U. S. P. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



2. AMIA OCCIDENTALS, DeKay. 



Western Mud-Fish, Dog-Fish. 



SPEC. CIIAK. Base of caudal fin without spot of any kind. Head constituting nearly the fifth of the total length. In 

 sertion of ventrals nearly equidistant between the base of the caudal and the extremity of the snout. Anterior margin of 

 the anal fin nearly equidistant, also, between the base of the pectorals and the posterior edge of the caudal fin. 



SYS. Amia occidentals, DEKAY, New Y. Faun. IV, 1842, 2G9; pi. xxxix, fig. 125. Cuv. & VAL. Hist. nat. Poiss XIX, 

 1846, 429. 



A specimen, twenty-six inches in total length and in the shape of a skin, otherwise well pre 

 served for zoological studies. It is referred, provisionally, to DeKay s species until further 

 investigations into the structure and habits of the other species shall enable us to determine 

 their systematic characters. 



List of specimens* 



Family SAUKLDAE,, DeKay. 



The skeleton in the fishes of this family is entirely ossified. The body is elongated, sometimes 

 very slender, and protected by lozenge-shaped scales of a bony base, and enamelled, smooth 

 surface, firmly united to one another, constituting one of the most impenetrable coatings ever 

 met with in the class of fishes. The jaws are furnished with rasp-like teeth, intermingling 

 with conical and acute ones. 



The ulterior zoological as well as anatomical characters of the gars (Lipidosteus) and Bichirs 

 (Polypterus) are so diversified that little else remains to be told respecting family traits ascribable 

 to both genera, and we should rather be inclined to adopt Miiller s suggestion in considering 

 either of them as the type of a peculiar family. 



SYN. Sauroides, Agass. Rech. Poiss. foss. II, n, 1833, 2 & 158. 



Sauroidei, AGASS. Nomencl. Zool. Pisces, 1844. MULL, in Wiegm. Archiv fur Naturg. 1843, 1, 327. 

 Sauridae, DEKAY, New Y. Faun. IV, 1842, 271. STOKER, Synops. 1846, 213. 



The fishes of this family constitute the order of Holostean ganoids of Professor Miiller,* 

 which he again divides into two families, the Lepidosteini of North America, and the Polypte- 

 rini of Africa, the only living representatives of this most remarkable group. By far more 

 numerous are the genera and species whose remains lie imbedded in the strata which compose 

 the earth s solid crust. 



LEPIDOSTEUS, Lace p. 



GEN. CHAR. Snout elongated; jaws somewhat unequal; upper one formed of numerous pieces; vomer double; lower jaw 

 composed of as many pieces as in the reptiles. Rasp-like teeth on the surface of the jaw bones, with long conical and acerated ones 

 at their edges. The vertebrae are anteriorly convex, and posteriorly concave. Nostrils near the apex of the elongated jaw. 

 A gill cover and a pseudo-branchia, but no spiracles. Four branchial arches, each provided with a double combed gill, and 

 between the last arch and the pharyngeal bones a split may still be seen. Three branchiostegal rays on either side. The 



* Wiegmanris Archiv fiir Naturgeschichte, 1845, 1, 119, & 137. 



