636 BULLETIN 129, UNITED STATES NATIONAL MUSEUM 



margin of carapace. Frontal region slightly convex, no protuberance 

 on orbital region. Rostrum short and blunt or faintly tridentate. 

 Orbits round, a closed fissure above. Basal joint of external antennae 

 about as long as next joint. Epistome concave. From the antero- 

 external angle of the buccal area a sharp, elevated, crenulated ridge 

 extends to outer base of chehped, separating concave pterygostomian 

 from subhepatic region, which is also concave and channel-like. When 

 retracted, the extremity of hand of cheliped covers pterygostomian 

 region, forming the afferent passage. External maxillipeds fit accu- 

 rately the buccal area and closely against each other within ; exognath 

 concave, forming part of wall of afferent channel, which is defined 

 within by a slight, elevated ridge on outer side of ischimn of endog- 

 nath; the merus has a prominent antero-external angle, its surface 

 concave toward antero-interior angle; no notch for insertion of palpus, 

 which, except at origin, is concealed behind the other joints of endog- 

 nath. The chelipeds resemble those of Parthenope, except that the 

 fingers are very small and the dactylus is generally at right angles 

 with palm when retracted. Terminal joints of ambulatory legs 

 acuminate. Third, fourth, and fifth joints of male abdomen soldered 

 together. 



American coasts, from Gulf of Mexico and the Bahamas to Bar])a- 

 dos, and at Panama. 



KEY TO THE SPECIES OF THE GENUS SOLENOLAMBRUS 



A^ Some teeth or spines on posterior or postero-lateral margins. Dorsal pro- 

 tuberances angular. 

 Bi. Not more than four teeth on posterior and postero-lateral margins. 



C^ Tubercles on surfaces of hand between crests. Dactylus oblique to 

 palm. Sternum between chelipeds with several tubercles. 



typicus, p. 537. 

 C^. Surfaces of hand smooth between crests. Dactylus at right angles with 

 palm. Sternum between chelipeds without tubercles. _arcuatus, p. 538. 

 B^. Six teeth or spines on posterior or postero-lateral margins. 



C. Six minute teeth on posterior and postero-lateral margins. No median 



spines. No spine near middle of branchial ridge. -portoricensis, p. 539. 



C^ Six spines on posterior and postero-lateral margins. Two median spines. 



A spine near middle of branchial ridge decemspinosus, p. 540. 



A-. No spines or teeth on posterior or postero-lateral margins. Dorsal pro- 

 tuberances rounded tenellus, p. 541. 



Analogous species on opposite sides of the continent: typicus 

 (Atlantic) ; arcuatus (Pacific) . 



