MUSEUM OF COMPARATIVE ZOOLOGY. 133 



region, which is also concave and channel like. When retracted, the 

 extremity of tluj hand of the cheliped covers the pterygostomian region, 

 forming the afferenl passage. The external maxillipeds fit accurately 

 the buccal area, and closely against each other within, and the exognath 

 is concave, forming part of the wall of the afferent channel, which is denned 

 within l>v a slight elevated ridge on the outer side of the ischium of the 

 endognath; the meros-joint has a prominent antero-external angle, and its 

 surface is concave toward the antero-interior angle, and there is no notch 

 for the insertion of the palpus, which, except at its origin, is concealed be- 

 neath the other joints of the endognath. The chelipeds resemble those of 

 Lambrus, except that the fingers are very small, and the dactylus is gener- 

 ally at right angles with the palm when retracted. The terminal joints 

 of the ambulatory feet are acuminate. The third, fourth, and fifth joints 

 of tin' male abdomen are soldered together. 



This genus differs from Parthenope and Lambrus in its naked, polished 

 carapax, in the distinct definition of the afferent channels, and in the want 

 of a notch in the meros-joint of the external maxillipeds tor the reception 

 of the palpus. As far as known, it is peculiar to the tropical portions of 

 the American seas, species being found on both the east and the wesl 

 coasts of the continent. 



Solenolambrus typicus nov. sp. 

 Carapax one eighth broader than long; posterior side considerably pro- 

 duced. Surface punctate. Protuberances of the gastric and cardiac 

 regions triangularly pyramidal, and acute, with the ridges forming the 

 angles crenulated; one of the ridges, the posterior. i> in the median line 

 of the carapax, and the other two diverge from each other in front. The 

 cardiac pyramid is symmetrical, each of its triangular sides being equal; 

 while the gastric protuberance is not symmetical, the posterior ridge being 

 a short, steep slope, and the two anterior ridges being long, and enclosing 

 a gradual, somewhat convex slope toward the trout. The ridge of the 

 branchial region is also crenulated, and is bent at the middle at an obtuse 

 angle, almost a right angle. In the male each of the protuberances of the 

 carapax is surmounted by an acute spine, while in the female the apical 

 angles are not thus acute. The margin of the carapax is more or less dis- 

 tinctly crenulated, especially the antero-lateral margin, at the outer or 

 posterior end of which there are three small out distinct teeth. The 

 antero-lateral margin is concave anteriorly and convex posteriorly. The 

 posterior margin is straight, with the lateral angles sharply defined, and 

 even spinifbrm in the male. Eyes rather large, with a minute tubercle on 

 the anterior side of the extremity. Basal joint of the external antennae 

 somewhat longer than the next joint. 



