THE SPIDER CRABS OE AMERICA 



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Description. — Carapace with 

 a cardiac and two median gastric 

 tubercles; a downward-pointing 

 tubercle or lamina on the hepatic 

 region. Rostrum hood-shaped, 

 thin, hoUuw beneath, a median 

 carina above. Postorbital tooth 

 small, tuberculiform ; behind and 

 below it a small tubercle. Ptery- 

 gostomian region protuberant, 

 more or less compressed and 

 prolonged in a tubercle at mid- 

 dle. Sternum of male with seg- 

 ments flattened and separated 

 by deep grooves: area in front 

 of abdomen subvertical, divided 

 into two protuberances which 

 are narrow, longitudinal and 

 parallel. Basal antennal article 

 gradually narrowed anteriorly, 

 longitudinally grooved tlirough 

 the middle. 



Chelipeds of adult male stout, 

 manus dilated, fingers narrowly 

 gaping in basal two- thirds; 

 chelipeds of female and imma- 

 ture male slender, manus not 

 dilated, fingers in contact. 

 Ambulatory legs of first pair 

 much the longest, about two 

 and a half times as long as 

 carapace, its merus stouter than 

 the others, dactylus about one- 

 fifth as long as the propodus, 

 unarmed, and much slenderer 

 and straighter than in the other 

 legs; second, third, and fourth 

 legs decreasing regularly in 

 length, the second twice or tw^o 

 and a fourth times, the fourth 

 leg about one and a half times 

 the length of the carapace; pro- 

 podites unequal, distal portion 

 slightly tliickencd and bent 

 upward, but straight, not con 



