DISCUSSION or SPECIES AND THEIR DIS TKIiiUTION. 497 



Structure. The basal portion of the cephalic, Mi)i)eu(lage is about twice as long as the very 

 small eye. The maxillary is a very slemhu', narrow bone, extending about as far backward 

 as the intennaxiUary. Tlie iutermaxilhiry is siigiitly protractile and lias about 10 teeth 

 on each side, several of which arc; nearly twice as large as the rest ; its lengtli is two-li(ths 

 of the total without caudal. The mandible is as loTig as the head without the snout; it has 

 S teeth <in each side, the anterior pair and several other ])airs along the shaft of tiie 

 boue being greatly enlarged. A (lair of enlarged teeth on tin; head of tin", vomer; several 

 similar teeth on the palatines. Iljiper i)haryngeals armed with several strong teetli. The 

 eye very small, inconspicuous; its distance from the tip of the snout ecpnils nearly one-third 

 its distance from the origin of the soft dorsal. Intestine sliortcr than length without caudal. 



The soft dorsal has 10 rays, all of which, (\\;cept the last lour, are greatly produced; 

 the second, tliird, and fourtii rays, are the longest; tliey ar(! nearly twice as long as the 

 body. The anal consists of 14 rays, all of which, excei)t tlie last three, are mucli produced. 

 The tin is not quite perfect, yet its anterior rays are longer than the body. The caudal 

 contains S rays, of which the four inner ones are divided, while the rest are simple. The 

 niiddle rays are as long as tlie distance from the tip of the lower jaw to the base of the 

 pectoral. The pectoral is comparatively sliort and contains Hi simjjle articulated rays, 

 the longest of which is about one-half as long as the head. 



About 9 luminous tilaments on <^ach sidcof the head, 7 more between the nape and 

 the dorsal, and about 12 on tlu', sides. The tilaments are nearly twice as long as the eye. 



Head and liody black; caudal cephalic tuft, and most of the tin-rays pale. 



The type of the species is number 3!l2Cr), taken by the steamer Albatross, JSepteinbcr 

 19, 1SS7, in N. lat. 39° 27', W. Ion. 71° 15', 1270 fathoms. 



Family ONCHOCEPHALID^^. 



MaltlKVoidci, Gill, Proc. Acad. Nat. Sil. I'bila., 1863,89 (diaguosis). 



Mallhamdw, Gill, Arrangement Families of Fishes, 187L', 2 (No. 10); I'roc. U. S. N. M., i, 1878, 215-219 (diag- 

 nosis) p. 231 (key to subfamilies and genera); v, 1883, 555 (witli elalxirato synonymy). 

 Mallhidw, Jordan and Gilbekt, Bull. 16, U. S. Nat. Mus... 841) (diagnosis and key). 

 Onchocc]tli(tlid(V, GiLL, MS. 



Pediculates with very broad and depressed Iicad, willi snout more or less elevated, 

 with trunk short and slender. Mouth not large, .subtermiual or inferior, tlie lower jaw 

 included; teeth villiform or cardiforni. Gill openings very small above and behind the 

 axils of the pectoral tins. Body and head covered with bony tubercles or spines. Spinous 

 dorsal reduced to a small rostral tentacle, which is retractile into a cavity under a pronu- 

 nent i)rocess on forehead; in one genus the rostral tentacle is obsolete; soft dorsal and anal 

 snuill and short; ventrals well develo])ed; pectoral well developed,its base strongly angled, 

 with long pseudobracliia and ;! actinosts. liranchiostegals .5; no i)seudobrancLiaj. 



KEY TO rilE SUBFAMILIES AND GENEKA. 



I. Body with disk cordiform and caudal iiortion stdiit. 



A. Frontal regiou elevated, and snout more or h'ss produeed or iitti^nnated forwards OnchoccphaVniO! 



1. Orhits lateral, teeth on vomer and jialatines. 



a Gills 2A « OxciiocKi'il AH'S 



h Gills 2 MAl.Tiiorsis (See Appendix.) 



II. Body with disk subeireular or expanded Ijaekwards ami .andal portion slender; frontal region depressed, 

 and snout rounded and olituse in front Ualieittwiiia- 



A. Palate edentulous; rostral teutaele developed; carpus cxserted lioni common membrane. 



1. Disk subeireular; gills 2J pairs. 



a. Mouth eleft wide, subvertieal. Priekles strong Halikct.ea 



6. Mouth small, terminal. Priekles feeble IIaukutki.LA 



2. Disk subtriangular ; month small ; gills 2 pairs DlBKA.vcill-S 



B. P,alate deutigerons ; dorsal li u obscdeti^ ; rostral tentacle present Hai.iomktl's 



C. Palate and vomer deutigerons ; dorsal present ; no rostral tentacle IlALiEfTlcuTUVS 



198(J8— No. 2 32 



