DISCUSSION OF SPECIES AM) THEIR DISTRIBUTION. 35 



b. Dorsal short, postmedian. Scales thin, radii inns I'm: m i pi hum; 



c. Dorsal short, median. Bod; naked Odontos iomid.k 



■ Vertebra; normal. Anterior neural spines abnormal 1> iU-vi-1oih-«1, projci tine, through the skin of the 



back, in advance of the dorsal. 

 l. Body compressed, ventradiform, carinated. 



a. Month obliqnely cleft, <>r sub vertical Stkhnoptyi im> .1. 



Vertebra? with spiny processes anteriorly •which projeol through the skin of the back in front of dor- 

 sal rays. 



1. Pectorals absent. Body elongate. 



a. Bodj naked. Dorsal beginning in advance of tho vent Iihacantuidje 



Family ALEPOCEPHALID^E. 



AUpocephales, Ccvier & Valenciennes, Hist. Nat. Poiss., xix. 169. 



AlepocephaluUe, Richardson, Encyc. Britannica, 8th ed., 1856, 255. — Gunther, Cat. Fish. Brit. Mus., vii, 



1868,477. — Gill, Arrangement, Families of Fishes, 17. — Jordan and Giubert, Bull, xvi, LT. s. Nat. Jin,., 



257. 

 Alepocephaloidei, Bleeker, Enum. Spec. Pise. Arch. Ind., 185H, xxx. 



Maiacopterygians with body more or less compressed, covered with thin cycloid or keeled 

 scales, or with naked, prickly skin. Head naked. No barbels. Month moderate or large, 

 the margin of the upper jaw formed by the premaxillaries and mamillaries, the former placed 

 along the upper anterior edge of the latter. Opercular apparatus complete. Teeth feeble. 

 No adipose tin. Dorsal fin long and low, posterior, inserted opposite the anal; pectorals 

 short, placed rather high; ventrals usually well back, sometimes wanting. Pseudo- 

 branchiae present. No air bladder. Stomach curved, without blind sac. Pyloric ececa in 

 moderate number. Gill openings very wide. 



KEY TO THE GENERA OF ALEPOCEPHALID^E. 



I. Body covered with scales. 



A. Ventrals present. 



1. Mamillaries toothless; month of moderate width ; scales thin, cycloid. 



a. Dorsal and anal similar and marly equal; body oblong Alepocephalus 



I i. Anal much longer than dorsal; body elongate CONOCABA 



2. Mamillaries toothed; month wide. 



a. Gill openings narrow, teetli in premaxilla and mandible uniserial Batiiytroctes 



b. Gill openings wide, teeth in premaxilla and mandible plnriserial Narcetes 



15. Ventrals absent; scales small, keeled; body abbreviated, liiyli, much compressed PLATYTROt i i - 



II. Hotly scaleless. 



A. Dorsal normal, equal in length to anal; scales replaced by nodules. 



1. Lateral line present Xenodermiciitiiys 



2. Lateral line absent Aleposo.mis 



B. Dorsal normal, shorter than anal Leptodbrma 



( I. Dorsal preceded by a long adipose fold Anomaxopterus 



III. Body with minute, hardly imbricate scales. 

 A. Pseudobranclme quite rudimentary. 



1. Bones of the head produced in a long snout AULOSTOMATOMORPHA 



ALEPOCEPHALUS, Risso. 



Alepocephalus, Risso, Mem. Accad. Nat. Sci. Turin, XXV, 1820, 270.— MOller, Abhandl. Akad. AViss. Berlin. 

 1846, 171. — Cdvier and Valenciennes, Hisr. Nat. Poiss., xix, 169.— GOnther, Cat. Fish. Brit. Mus., 

 vii, 177.— Jordan and Gilbert, Bull, xvi, r. s. Nat. Mus., 257. 



Body oblong, compressed. Month moderate, the snout somewhat prolonged, .laws 

 Dearly even in front; a series of small teeth in each jaw and on tlie vomer and palatines. 

 Eye very large. Gill membranes entirely separate. Branchiostegals 6. Opercular bones 



thin. Dorsal low and rather long, with a scaly base, opposite and similar to the anal. Pec 

 torals and ventrals rather small. Caudal moderately forked. Scales rather large, thin and 

 cycloid. 



