2. Dorsal median groove of the carapace is narrower than 

 the lateral grooves. Central plate of the thelycum has a 

 forked, calcified appendage at the anterior end. Lateral 

 plates meet at the median line of the body, forming the 

 sides of the longitudinal opening of the seminal receptacle. 

 Appendage of the spermatophore is a narrow fibrous band. 

 Anterior end of the internal lamina of the petasma does 

 not extend beyond the external lamina. Rostrum loorii 

 dentate above. 



P. latisulcatiis. 



B. Three teeth on the inferior margin of the rostrum. Lateral 

 grooves of the carapace run only half the length of it. Per- 

 eiopoda slender. Posterior end of the internal lamina of the 

 petasma is produced to a short straight protuberance. First 

 pair of pereiopoda bispinose, the second pair unispinose. 



3. . Dorsal median groove of the carpace present. Lateral 

 grooves terminate a little behind the gastric tooth. Flagel- 

 lae of the first pair of antennae shorter than the peduncle 

 of the same. Lateral plates of the thelycum meet at the 

 median line of the body. Very minute teeth near the 

 anterior external margin of the . petasma. Rostrum 7 

 dentate above. 



, P, ashiaka. 



4. Dorsal median groove of the carapace wanting. Lateral 

 grooves are lost near the level of the gastric tooth. 

 Flagellae of the first pair of antennae longer than the 

 peduncle of the same. Central and lateral plates of the 

 thelycum meet in Y shaped lines. Outer rim of the 

 petasma is bent, pointed and has some very minute teeth 



