Jordan and Evermann. Fishes of North America. 2451 



connected with the caudal by a very delicate membrane. Distance from 

 origin of dorsal fin to occiput 3 times the length of the head, its rays dis- 

 tinct, connected by thin transparent membrane, as are the rays of the 

 anal; most of the rays simple and undivided (but mostly articulate), a 

 few of the posterior only forked at tip; origin of anal fin nearly equidis- 

 tant between, gill rakers and tip of caudal, its rays mostly forked at tip; 

 caudal rays much divided and more closely set than thoso of dorsal and 

 anal, the fin somewhat pointed in outline, as long as the head ; tail not 

 isocercal, truncate at base of caudal fin; ventral fins very small, close 

 together, inserted slightly behind base of pectorals; each fin reduced to 

 a single undivided filament ; pectoral fin small, pointed, the middle rays 

 longest, much shorter than the ventrals, and \ the length of the head. 

 Vent considerably behind middle of total length of the fish (with cau- 

 dal). Head and body covered with scattered rudimentary scales. Color in 

 life, translucent light olive, with a series of irregular quadrate dark 

 blotches along the back and a series along each side, these blotches formed 

 of clusters of dark points. One specimen, nearly 4 inches in length, was 

 taken in a rock pool at Panama; others since taken by Dr. Gilbert. This 

 species differs from the description of the previously known Microdesmus 

 dipus, Giinther, in the posterior insertion of the dorsal and the posterior 

 position of the vent, the smaller number of fin rays, the shorter head, 

 longer ventrals, and mottled coloration, (retro, backward; pinna, fin.) 



Microdesmus retropinnis, JORDAN & GILBERT, Bull. U. S. Fish Comm. 1881, 331, Panama. 

 (Coll. C. H. Gilbert.) 



Family CCIV. PTILICHTHYID^E. 

 (THE QUILL-FISHES.) 



Body extremely elongate, serpentiform, little compressed, the tail taper- 

 ing to a point. Skin with a few thin, loose, scattered scales; no lateral 

 line. Head unarmed, rather small ; upper jaw not protractile; snout short; 

 mouth oblique; lower jaw projecting considerably beyond the upper, 

 with a protruding fleshy appendage at tip. Maxillary reaching front of 

 eye. Mandible little movable. Both jaws with fine, close-set, sharp teeth, 

 in 1 row, the posterior teeth a little the largest; no evident teeth on 

 vomer or palatines. Gill openings restricted to below the most convex 

 part of the opercle, the membranes broadly united below, free from the 

 isthmus. Gills 4, a slit behind the fourth. Pseudobranchia) very small, 

 almost obsolete. Gill rakers short and stout. Pectorals short; ventrals 

 wanting ; dorsal beginning close behind the nape, the anterior portion 

 for about i the length of the body composed of very low, stiff, free spines, 

 hooked backward, the posterior portion higher, of slender soft rays con- 

 nected by thin membrane. No caudal fin, the tip of the tail free. Anal 

 similar to the soft dorsal, without spines. Vent at considerable distance 

 from the head. North Pacific. A single species known. 



Concerning the relationships of this interesting group, Dr. Gilbert 

 observes : 



"The genus Ptilichthys, of which this species [P. goodei] is the sole repre- 

 sentative, has been doubtfully referred by Dr. Beau to the Mastacembdidw, a 



