DISCUSSION OF SPECIES AND THEIR DISTKIIJUTION. IGl 



Order CARENCHELYl. 



Carenchelyi, Gill, MS. 



Teleost fishes with tlie iiitermaxinaries and supramaxillaries developed and united by 

 suture, and immovably cDnnected with tlie cianium; branchial a])paratus as in Apodes; 

 scapular arch remote from the skull, and the body angnilliform. ((Uli, ms.) 



Family DERICHTHYID^E. 



Derichthyidw, Gill, American Naturalist, v, 18, 433, 1884. 



Body anguilliform, slender, with a. neek-like contraction between the head and pectoral 

 fins, and submedian anus. Scales absent, the skin being perfectly smooth. Lateral line 

 commencing on the side, behind the head, near the back, but submedian behind. 



Head oblong, oval. Eyes in the anterior half of the head. Nostrils lateral, in front of 

 the eyes; neither tubular. Mouth with the cleft little oblique, extending behind the eyes. 

 Jaws well developed, niaxillaries approximated to the front of the vomer and attenuated 

 backwards. Mandible moderately stout; the dentary with the coronoid process moderate 

 and not far from posterior end. Teeth conic, in cardiform bands on the jaws and vomer. 

 Lips moderate. Tongue moderate. Periorbital bones. 



Opercular apparatus moderately developed; operculum inserted rather low on the hyo- 

 mandibular by a peiluncle, horizontally oblong, with emarginate upper edge and convex 

 lower one; suboperculum curved and applied below operculum; interoperculum long, con- 

 nected in front with angle of jaw and behind with front of suboperculum; ])reoperculum 

 moderate. 



Branchial apertures lateral ; vertical slits in front of pectorals. 



Branchiostegal rays in small number (about (5), rather slender and curved upwards 

 behind the opercnla. 



Dorsal, anal, and caudal confluent in an uninterrupted fin; dorsal commencing far 

 behind the head; anal commencing about midway between snout and end of tail or middle 

 of body; caudal pointed and reduced. 



Pectorals inserted nearer the breast than back, narrow and rather long, with about 

 10 or 11 fine rays, and bent forward. 



Branchial arches slender; glossohyal moderately long; urohyal very slender and 

 pointed; first basibranchial very long; second and third basibrancliials moderate; epipha- 

 ryngeals reduced to a pair(?); hypo] )haryngeals long and closely appressed and superin- 

 cumbent on the rudimentary fifth arch. 



DERICHTHYS, Gill. 

 Derichthya, Gill, American Naturalist, xviii, 1887, 433. 



The generic characters are included in the family diagnosis. 



DERICHTHYS SEEPENTINUS, Gill. (Figure 169.) 



Derichthijs serpentinus, Gill, American Naturalist, x\'iii, 1887, 433. 



Body stout, somewhat compressed, especially behind the vent; its greatest height in 

 the region of the vent nearly equal to the length of the head; its postanal portion eciual to 

 the distance from the vent to the posterior margin of the orbit. 



Head small, snake-like, its resemblance to that of a serpent being enhanced by the con- 

 tracted neck-like appearance of the anterior portion of the boily. Its anterior portion is 

 depressed, and the view from above abruptly truncate, the width of the tip of the snout 

 being considerably greater than the interorbital space. The lower jaw is narrower and in- 

 cluded, the upper jaw projecting lieyond its tip a distance nearly ('(pial to the diameter of 

 the eye. The length of the snout is one third that of the head. The clelt of the month ex- 

 tends behind the eye a distance equal to or slightly greater than the diameter of the orbit. 

 19868— No. 2 11 



