248 BULLETIN IGG, UNITED STATES NATIONAL MUSEUM 



HEPATELLA PERUVIANA Rathbun 



Hepatella arnica Rathbun, not Smith, Proc. U. S. Nat. Mus., vol. 38, p. 552, pi. 



50, fig. 5, 1910. 

 Hepatella peruviana Rathbun, Proc. Biol. Soc. Washington, vol. 46, p. 183, 1933 



(type locality, Bay of Sechura, Peru; U.S.N.M. no. 40451). 



Description. — Carapace narrow, edge thin, front more produced and 

 orbits more dorsal than in arnica. Protuberances small, one oblong 

 and granulate on each branchial region; one round on cardiac region 

 and crossed by a transverse line of granules ; three small, granulate, on 

 gastric region, the median behind the lateral pair. Anterolateral 

 teeth regular, subtruncate ; a broad tooth near anterior end of postero- 

 lateral margin, a thicker, more prominent tooth at end of posterior 

 margin. 



Measurements. — Female holotype (40451), length of carapace 18.2, 

 width 20 mm. 



Range. — Panama to Peru. 



Material examined. — See table 80, page 249. 



Genus OSACHILA Stimpson 



Osachila Stimpson, Bull. Mus. Comp. Zool., vol. 2, p. 154, 1871 (type, 0. tuberosa 

 Stimpson) . 



Near Hepatus in all essential characters, but differs in the narrower, 

 octagonal carapace, more or less depressed and expanded at sides; 

 very uneven surface having usually six chief protuberances; and the 

 much produced front, forming a true rostrum. 



From North Carolina to northwest Florida and Windward Islands; 

 eastern Atlantic; Cape San Lucas to Panama; Hawaiian Islands; 13 

 to 164 fathoms. 



KEY TO THE AMERICAN SPECIES OF THE GENUS OSACHILA 



A'. Length of carapace more than three-fourths of its width. 

 Bi. Rostrum thick, bilobed. 



C. Dorsal surface of carapace wholly eroded. 



D'. Cardiac elevation pointed behind antillensis (p. 251) 



D2. Cardiac elevation rounded behind galapagensis (p. 254) 



C". Dorsal surface of carapace partly eroded, including eleva- 

 tions. Cardiac elevation rounded behind. 

 D*. Posterolateral margin thin-edged. Outer surface of 



manus largely reticulated tuberosa (p. 250) 



D^. Posterolateral margin thick. 



E'. Dorsal protuberances high, six in number. Outer sur- 

 face of manus with five rows of tubercles semilevis (p. 251) 



£2. Dorsal protuberances more than six. Outer surface 



of manus with 10 or 12 rows of granules levis (p. 254) 



B^. Rostrum thin, sharp-edged, denticulate. Outer surface of 



manus with five longitudinal ridges acuta (p. 257) 



A^. Length of carapace three-fourths of its width. Manus sparingly 



tuberculate lata (p. 257) 



