116 >S. J. Smith on American Cnistacea. 



A. — Species in which all the sejments of the abdomen are separated by distinct articula- 

 tions, and in ivhich the front is very much contracted between the bases of 'the ocular 

 peduncles and somewhat spatulate in form. 



Gelasimus heterophthalmus, sp. nov. 



Plate II, figure 6, 6^ Plate III, figure l-l^ 



Male. The carapax is somewhat quadrilateral iu outline, but the 

 antero-lateral angle on the side of the larger cheliped is much produced 

 laterally, so that the orbit is much longer on that side than on the 

 other and the lateral border strongly divergent. The dorsal surface 

 is smooth and shining, and convex longitudinally but not at all late- 

 rally. The branchial regions are very slightly SAVollen, scarcely high- 

 er than the gastric and cardiac regions, and are separated from them 

 by slightly marked sulci. The front is spatulate, contracted between 

 the bases of the ocular peduncles and much expanded below. The 

 superior border of the orbit is much excavated at the base of the ocu- 

 lar peduncle, and strongly arcuate in the middle, and has a very slight- 

 ly upturned and entire margin. The antero-lateral angle on the side 

 of the smaller cheliped, is angular but does not project either anteri- 

 orly or laterally, while on the side of the larger cheliped it is broad, 

 obtuse and projects very much laterally, as described above. The 

 lateral margin is obtuse and its posterior part only is indicated by a 

 faint granulous line. The upper part of the inferior branchial region 

 is oblique, flat and very smooth, and is separated from the lower por- 

 tion by a slightly raised line running straight from the antero-lateral 

 angle to the base of the third pair of ambulatory legs. The inferior 

 border of the orbit is denticulate with minute, flattened and truncate 

 teeth. The jugal regions are smooth and shining. 



The ocular peduncles are rather slender, slightly enlarged at the 

 cornea, and the one on the side of the larger cheliped is consider- 

 ably the longer and is terminated beyond the cornea by a very slen- 

 der filiform stylet, much longer than the peduncle itself, and slightly 

 flattened and expanded at the tip. There is no trace of a terminal 

 stylet on the peduncle of the other side. 



In the larger cheliped, the anterior surface of the merus is smooth, 

 narrowly triangular in outline and considerably convex, the inferior 

 margin is sharp and denticulate, and the superior margin is armed 

 with a slight crest which is very low and entire for most of its length 

 but quite high, and in some specimens slightly dentate, at its distal 

 extremity. The carpus is short and its upper surface is slightly ver- 

 rucose. The basal portion of the propodus is rounded and coarsely 



