l^Q BULLETIN 166, UNITED STATES NATIONAL MUSEUM 



Genus LITHADIA Bell 



Lithadia Bell, Trans. Linn. Soc. London, vol. 21, p. 305, 1855 (type, L. cuviingii 

 Bell). 



Carapace subrhomboidal, with cardiac region produced posteriorly, 

 lateral margins produced over bases of legs; surface very uneven, 

 branchial and cardiac lobes elevated, hepatic region much depressed; 

 the subhepatic region forms a distinct and obhque facet; surface 

 rough with granules or tubercles. Front produced, narrow, upturned, 

 orbits small; a considerable space between edge of lower wall of orbit 

 and free edge of buccal cavern. Merus of external maxillipeds much 

 more than half the length of ischium measured along inner edge; 

 outer margin of exognath nearly straight. Chelipeds rather short 

 and heavy. Segments 3-5 in abdomen of male fused, 4-6 of female. 



This genus is restricted to those species which have marked excava- 

 tions on the upper surface of the carapace. 



East and west coasts of Middle America; South Africa (Stebbing), 

 Indian Ocean (Laurie), Australia (Haswell). 



KEY TO THE AMERICAN SPECIES OF THE GENUS LITHADIA 



A'. An anterior median carina on carapace. 



B'. Major part of carapace excavate; highest points, 2 small lobes 



in line with widest part of carapace cumingii (p. 136) 



B^. INIajor part of carapace convex. Branchial region almost 



entirely swollen. Rostrum slightly concave cadaverosa (p. 137) 



A^. No anterior median carina; highest point a small branchial 



pyramid either side in line with widest part of carapace granulosa (p. 140) 



LITHADIA CUMINGII Bell 



Plate 38, Figures 1, 2, 7-15 



Lithadia cmningii Bell, Trans. Linn. Soc. London, vol. 21, p. 305, pi. 33, fig. 6, 

 7, 1855 (type locality, Puerto Portrero, Central America [Potrero, Costa Rica]; 

 type in Mus. Bell).— Rathbun, Proc. U. S. Nat. Mus., vol. 21, p. 613, 1898. 



Diagnosis. — Major part of carapace excavate. Anterior median 

 carina a single line of granules. Rostrum with two narrow arcuate 

 lobes. Highest points of carapace two small lobes opposite widest 

 part of carapace. 



Description. — Male: Carapace very strongly marked by rude 

 elevations, sharply circumscribing deep hollows. In a young male 

 the elevations are more numerous and distinct, and the sulci separating 

 them are continuous; in an old male these elevations are confluent, 

 the sulci becoming four irregular circumscribed hollows, covered 

 within with distinct granulations. Intermediate stages have been 

 noted. Posterior branchial lobe forming a triangular tooth; lobes 

 of posterior margin similarly modified. Rostrum slightly turned up, 

 emarginate. Outer maxillipeds, sternum, and abdomen covered 

 with distinct large and elevated granulations. The fused segment of 

 male abdomen has a minute tooth at posterior angles and a slight 



