MAIOIDEA. 87 



two-thirds the length of the carapax; posterior pair one and one-fourth 

 times the same, and but little longer than first pair. 



Ilyas lyratus, DANA, Silliman's Am. J. Sci., 2d Ser., si. 268. 



PISOIDES EDWARDSII (Bell), Dana. 



Plate 1, fig. 2 a, under view of head, much enlarged ; b, outer max- 

 illiped. 



Valparaiso. 



This species, as described by Bell and Milne Edwards, under diffe- 

 rent names, is short and thick hairy, and has a flattened pyriform 

 shape. One specimen, a male, is sixteen lines long, and twelve lines 

 greatest breadth, the beak four lines or one-fourth whole length. 

 Another specimen nine lines long, had for its greatest breadth seven 

 lines. 



The beak is flattened, with the horns evenly and slightly divergent 

 and setigerous within. The first joint of the outer antennas is sub- 

 quadrate nearly as in the Periceridse, with the outer angle projecting 

 as in Tiarinia. The second joint is full twice as long as the third, 

 and both are flattened and ciliate on the outer side, the third being 

 ciliate on both margins. The outer angle of the first joint is set with 

 minute spinules or hairs, and a prominence at posterior angle is rag- 

 gedly but minutely denticulate. 



The exterior maxillipeds are pubescent, and the outer margin of 

 the palpus has a re-entering angle a short distance from its upper 

 extremity. 



The legs have a fringe of rather short hairs on opposite (upper and 

 lower) margins. The branchial regions are tumid, and there are two 

 or three faint tubercles of small size. The cardiac region is a broad 

 prominence with a rounded surface, and either side a little posteriorly 

 there is a small tubercle. The stomach region is prominent with a 

 low posterior tubercle, and another oblong one anteriorly equally dis- 

 tinct. Outer orbital acanthus acute. Intestinal region with a small 

 tubercle, but all the tubercles concealed mostly by the villosity of the 

 surface, so as not to be seen unless it is removed. 



