GRAPSID^ 6l 



Opisthopus transversus Rathbun. 



Opisthopus transversus Rathbun, Proc. U. S. Nat. Mus., xvi, 252, 1893. — Holmes, 

 Occas. Papers Calif. Acad. Sci., vii, 97, 1900. — Rathbun, H. A. E., x, 188, 1904. 



There are numerous specimens of this species in the collection in part 

 from Stichopus calif ornicus, a common Holothurian, and Lucapina cren- 

 ulata, the large key-hole limpet. The distinctness of the suture between 

 the ischium and merus of the outer maxilliped varies considerably. All 

 have a more or less clearly defined patch of pubesence along a portion of 

 the antero-lateral margin. The abdomen in the females at hand varies 

 from a width greater than that of the carapace to a size no greater than 

 that of the male. This does not seem wholly due to immaturity as some 

 of the females with narrow adbomens are carrying eggs. A tendency in 

 the hand to approach in shape that of the male accompanies the narrow 

 abdomen. 



Family GRAPSIDyE. 

 Key to genera. 

 a. Carapace considerably broader than long. 



b. Carapace transversely striated, external maxillipeds with a wide 



rhomboidal gape between them. Pachygrapsus 



bb. Carapace smooth, external maxillipeds closely approximated 



along inner edge. Hemigrapsus 



aa. Carapace as long or longer than broad. Planes 



Genus PACHYGRAPSUS Randall. 



Pachygrapsus Randall, Jour. Acad. Nat. Sci. Phila., viii, 127, 1839 (Type — Pachy- 

 grapsus crassipes Randall). 



t Pachygrapsus crassipes Randall. 



Plate XIII, fig. 41. 



Pachygrapsus: crassipes Randall, Journ. Acad. Nat. Sci. Phila., viii, 126, 1839.' — 

 Holmes, Occas. Papers Calif. Acad. Sci., vii, 79, 1900, and synonymy. — Rath- 

 bun, H. A. E., X, 189, 1904. 



