612 Bulletin ^7, United States National Museum. 



bands on intermaxilla, mandible, and voraer j in narrower bands on max- 

 illa and palatines. End of tongue barely free. Integumentary flap pro- 

 jecting beyond margin of suboperculum. Dorsal beginning about over 

 end of the base of ventral, its distance from tip of snout a little more 

 than twice length of head ; length of its base nearly equal to greatest 

 depth of head ; basal half of the fin profusely covered with scales ; it 

 consists of 2 simple and 9 divided rays. Longest dorsal ray (1 inches) 

 equals f greatest height of body, last ray % as long as third. Ventral dis- 

 tant from the snout a space about equal to twice head; it consists of 2 

 simple and 1 divided rays, the longest equal to base of dorsal; pectoral 

 placed above middle of body, not far from head, its length equal to \ 

 distance of its base from origin of ventral, and reaching to about seven- 

 teenth row of scales. Vent under sixty-third scale of lateral line ; about 

 12 rows of scales between origin of dorsal and lateral line and about 2 

 rows between lateral line and origin of ventral ; lateral line composed of 

 enlarged and modified scales, becoming obliterated about middle of tail; 

 15 or 16 of these enlarged scales between head and origin of ventral ; 

 about 27 between vent and head ; distance from origin of ventral to anus 

 (3 inches) nearly equal to head. Anal rays about 166, their origin not far 

 behind vent; caudal, which is long and slender, with about 4 rays ; pec- 

 toral 13. Membrane covering anal rays scaled throughout almost its entire 

 length. Gill rakers rather short and few, 3 -j- 12. Color of scales a light 

 silvery gray, through which the body color appears as a light orange- 

 brown; branch iostegal membrane and opercular bones bluish; inside of 

 gill covers very dark blue. The type, a specimen two feet long, taken 

 in the Gulf of Mexico, 24 36' N., 84 05' W., by the Blake at Station 173, 

 at a depth of 955 fathoms. Many others were obtained in the Gulf Stream, 

 in depths ranging from 679 to 1,430 fathoms, by the Albatross. (Goode 

 & Bean.) (pallidus, pale.) 



Aldrovandia pallida, GOODE & BEAN, Oceanic Ichthyology, 134, 1895, Gulf of Mexico. (Co-type, 

 No. 38140. Coll. Albatross.) 



Order V. HETEROMI. 

 (THE SPINY EELS.) 



The Notacanihidce* are separated from the other physostomous fishes by 

 Gill, to form an order which he thus defines : 



* Some recent American authors have placed the Notacanthidse with the physoclystous family 

 of Mastacembelidse in the order Opisthomi of Cope, originally framed for the latter. There seems, 

 however, to be no evidence, as Dr. Vaillant has lately noted, of affinity between the Mastacembe* 

 lidse and the Notacanthidse. Vaillant calls attention to the presence of an air duct in Notacanthus, 

 and places the family among the Ganoids, between the Sturgeons and the Eels. According to 

 Vaillant (Exped. Sci. Travailleur et Talisman, 324) the dorsal spines in Notacanthm differ widely 

 from those of Teleostean fishes in having but a single nourishing canal instead of two. He finds 

 these spines homologous with the plates of sturgeons or rather with the pinnules of the Ganoid 

 genus Polypterus, instead of with the spines of the physoclystous fishes. Vaillant also findsmany 

 of the skeletal characters of Notacanthus very primitive, suggesting Ganoid affinities. At the 

 same time, the simple air bladder, the absence of spiral valve in the intestines and of multiplied 

 valves in the heart seem to ally Nolacanthus rather to the Isospondyli or the Eels. Giinther 

 places it among the Physostomi between the Halosauridse and the eels, but does not regard it as 

 having close affiuities with either. 



