The Isopods of the Pacific Coast of North America. 321 



seem to have been well ossified, but much constricted, and all 

 those preserved belong to the abdominal region. Nothing 

 can be added to the description of the dorsal scutes given by 

 Davis ; but appearances suggest that at the broken hinder 

 end of the fossil the row of scutes terminates, while the dorsal 

 fin begins. The only scales shown are those of the two 

 swallowed fishes in the abdomen. 



On the whole, it seems probable that Pantopholis will prove 

 to be a member of the same extinct family of Scopeloids as 

 Enchodus. It is remarkable for the length and slenderiiess 

 of the abdominal region, the large size of the pectoral fins, 

 and the unusually numerous median dorsal scutes. 



XXXIV. — Key to the Isopods of the Pacific Coast of North 

 America, xoith Descriptions of Tvoenty-tijoo new Species. By 

 Hareiet Richardson. 



[Concluded from p. 277.] 



IV. ASELLOTA. 



Analytical Key to the Families of Asellota*. 



a. Lateral parts of ceplialon scarcely expanded. 

 Eyes, when present, small, lateral. Peduncle 

 of inferior antennre without small accessory 

 appendage outside of third joint. Legs ambula- 

 tory, except first pair, which are distinctly sub- 

 cheliform ; legs with dactylus generally uniuugiii- 

 culate. First pair of pleopoda in female very 

 small, not operculiform. Outer lamella of second 

 pair very large and iucrusted, so as to form, 

 together with corresponding lamellce of other 

 side, a sort of operculum, covering the two suc- 

 ceeding pairs XI. AsELLiDuE. 



%', Lateral parts of cephalou usually lamellar ly ex- 

 panded. Eyes, when present, usually subdorsal. 

 Peduncle of inferior antennae generally with 

 small accessory appendage outside of third joint. 

 Legs subequal in length with dactylus, generally 

 bi- or triuno:uiculate ; first pair sometimes 

 prehensile. First pair of pleopoda in female 

 transformed into a single large opercular plate. 

 Outer lamellae of two succeeding pairs narrow 

 and confluent with basal part XII. Janirid^. 



• Sars, Crust, of Norway, ii. 1897, pts. 6, 6, pp. 95, 98. 



