128 University of Washington Publications in Biology [Vol. 2. 



96b. Body oblong, short and deep, compressed, truncate be- 

 hind so there is no caudal peduncle ; dorsal not extending 

 along the back as in 96a; gill openings in front of the 

 pectoral as is usual in fishes. 

 Head Fish. Ocean Sunfish 88. Molidae, p. 197 



90b. Gill membranes free from the isthmus or with a wide free fold across 

 isthmus, or continuing forward before becoming joined. Fig. 12. 



99a. Caudal fin not widely forked or lunate ; least depth of caudal pe- 

 duncle if present fewer than 6 times in greatest depth of body ; depth 

 of body more than 2.5 times in the standard length. 



100a. Dorsal rising so gradually from the back that its beginning is 

 scarcely evident. 



101a. Dorsal and anal not reaching to caudal; caudal peduncle slen- 

 der, caudal fin concave behind. 

 Great Ray Fishes 57. Acrotidae, p. 161 



101b. Dorsal and anal connected with caudal fin. 



102a. Tail tapering to a point and with a caudal filament (usually 

 broken off preserved specimens) ; head about 16 in length 

 without filament. 

 Quillfish 83. Ptilichthyidae, p. 195 



102b. Tail rounded; head about 8 in length. 



Burrowing Blennies 82. Scytalinidae, p. 195 



100b. Beginning of dorsal fin evident, rising more or less abruptly. 



103a. Gill membranes broadly united to each other. 



104a. Dorsal fins 2. 



Sculpins 68. Cottidae, p. 172 



104b. Dorsal fin single. 



105a. No sucking disk on breast. 



106a. Small imbricated scales on gill membranes, all over 

 body and on the fins except the distal third ; dorsal 

 fin of very flexible spines ; depth of body about 3 to 

 4 1 /- in length. 

 Flaccid Fishes 77. Zaproridae, p. 191 



106b. Scales if present usually embedded and never occur- 

 ring on gill membranes nor on the fins ; dorsal fin 

 spines not flexible ; depth of body more than 5 times 

 in the length. 



107a. Origin of anal fin under the 34th to 55th spinous 

 ray of dorsal fin ; body ribbon-like and never with 

 multiple branched lateral lines ; all vertebrae with 

 haemal arches. 

 Blennies 79. Pholididae, p. 192 



