FISHES SAUEIDAE LEPIDOSTEUS LEPTORHYNCHUS. 351 



anterior margin of all the fins exhibits a double row of spine-like scales. The insertion of the caudal fin is oblique ; a portion 

 of its rays being inserted at the extremity of the vertebral column ; the other portion under it. The dorsal is inserted far back, 

 opposite the anal fin. The ventrals are abdominal. The stomach has no cwca ; the pylorus having numerous short appendages. 

 The intestine recurs twice upon itself. The air bladder is cellular, and through an elongated split it communicates with the upper 

 wall of the throat. 



Syy.Lfpidosteus, LACEP. Hist. nat. Poiss. V, 1803; ed. 800, IV, 1819, 59. Cuv. R5gn. Anim. II, 1817, 181 ; 2d ed. II, 

 1829 ; &, ed. Illustr. Poiss. 286. AGASS. Eech. Poiss. foss. II, ii, 1833, 4 ; &, Lake Super. 1850, 254. 

 DEKAY, New Y. Faun. IV, 1842, 271. MULL, in Wiegm. Archiv fur Naturg. 1845, I, 119. STOKER, 

 Synops. 1846, 213. BUM. Ichthyol. analyt. 1856,434. 



For years past ichthyologists have been looking forwards for a promised monograph of this 

 genus by Professor Agassiz, and since his studies of this peculiar group must necessarily be 

 based upon a large amount of material, they would have proved of great assistance to us in the 

 preparation of the present report. The above diagnosis is derived chiefly from Professor 

 Midler s description of this genus. 



There are three well marked groups in the genus Lepidosteus; the first one is characterized 

 by a very narrow and prolonged snout, the mouth being longer than the head, properly so called,, 

 with but one row of larger teeth at the upper as well as lower jaw : Lepidosteus oxyurus is the 

 type of this group. In the second group (Cylindrosteus] the snout is depressed, rather broad, 

 equal in length to the head, properly so called,, with but one row of larger teeth at the upper 

 as well as at the lower jaw : Lepidosteus platostomus is the type of this second group. Finally, 

 the third group (Atractosteus ) is characterized by a very broad snout, nearly equal in length to 

 the rest of the head, or somewhat longer, with two rows of larger teeth at the upper jaw : 

 Lepidosteus ferox being the type of this group. 



1. LEPIDOSTEUS LEPTORHYNCHUS, Grd. 



SPEC CHAR. Body anterior to the ventrals cylindrical, and posteriorly deeper than broad (thick) ; dorsal region sub-concave, 

 broader than the abdominal region. Peduncle of tail very much compressed. Head constituting a little less than the third 

 of the total length. Eyes well developed, sub-elliptical; horizontal diameter of the orbit entering fifteen times and a half in the 

 length of the side of the head ; nearly thrice and a half time behind its posterior rim. Anal smallar than the dorsal ; either 

 of these fins not extending the tip of their longest rays as far as the base of the caudal. Ventrals much larger than the 

 pectorals, inserted further apart the thoracic belt than the anterior margin of the anal, and much nearer the posterior edge 

 of the caudal than the tip of the rostrum. Olivaceous, upper regions spotted with black. 



The specimen before us measures from thirty-four to thirty-five inches. The head is slender, 

 very much depressed, broader than deep, tapering gradually forwards into an elongated 

 rostrum. The upper jaw projecting beyond the tip of the lower one, which is entirely overlapped 

 when the mouth is closed. The lower jaw is a great deal more than twice the length of the 

 rest of the side of the head, although not quite twice and a half as long. One series of large 

 conical and acute teeth may be observed right and left on either jaw, with an external series 

 of much smaller teeth. The inner edge of the dental groove exhibits at the lower jaw two series 

 of rasp-like teeth, the innermost of which is more slender than the other, whilst at the upper jaw 

 there is but one series of similar teeth, resembling those of the slender kind just alluded to. 



The dorsal and anal fins are of moderate development, much higher or deeper than long. 

 The ventrals are more stoutly built and much larger than the pectorals. 



D 7; A 8; 012; V 6; P 12. 



The rays in all the fins are very strong, sub-divided and branched off ; the outermost pectoral 



