MUSEUM OF COMPARATIVE ZOOLOGY. 9 



able number of low obtuse spines or tubercles. The cardiac region is separated 

 from the branchial each side by a deep sulcus, is prominent and armed with 

 two pairs of large spines, and back of these with a single one in the middle line. 



The eyes, antennulse, antennse, and the exposed parts of the oral appendages 

 are very nearly as in L. maia. The chelipeds are nearly equal in length, but 

 the right is much stouter than the left, are armed with comparatively few and 

 small spines, and the digits of the chelae are about two thirds of the entire 

 length of the chela, slender, tapering, and strongly curved. The ambulatory 

 legs are very long, those of the third pair being nearly three times as long as 

 the breadth of the carapax excluding spines. The ischial, meral, and carpal 

 segments are armed with only a very few scattered and very small spines, the 

 meral segments in the first and second pairs are almost entirely unarmed ex- 

 cept a few small spines or teeth along the upper edges, but the propodi, which 

 are slender and fully as long as the corresponding meri, are armed along the 

 edges with more numerous and very sharp but small spines. The dactyli are 

 about half to considerably more than half the length of the corresponding pro- 

 podi, slightly curved, acute, and, except near the tips, armed with small and 

 acute spines. 



The plates of the second somite of the abdomen are armed with numerous 

 spines projecting backward and upward, and of which those upon the middle 

 plate are longer than those upon the lateral. The plates of the succeeding 

 somites of the abdomen are very unequally developed, the plates of the left 

 hand side of the third, fourth, and fifth somites being greatly developed at the 

 expense of the corresponding plates of the opposite side, so that the outer edge of 

 the left side of the fifth segment lies beneath the bases of the cheliped and first 

 ambulatory leg of the right side, and the small semicircular telson is beneath 

 or a very little in front of the base of the second ambulatory leg of the right 

 side. 



In the smaller of the adult specimens (PI. I. fig. 1) the carapax, excluding 

 rostrum and spines, is proportionally narrower than in the larger specimen, 

 being about eight tenths as broad as long, and the spines upon the carapax, 

 abdomen, and appendages are much longer and more numerous, the additional 

 spines appearing between the large ones corresponding to the spines, or in 

 place of the tubercles, on the larger specimen. The rostral spine and the 

 spines at its base are absolutely more than twice as long as in the larger speci- 

 men and more slender, and about the same proportion holds for all the principal 

 spines of the carapax. The external angle of the orbit projects in a spine but 

 little shorter than the eye-stalk, and back of it there are two nearly as large 

 spines on the antero-lateral margin in place of the two angular prominences of 

 the larger specimen. The large hepatic spine and the thirteen large marginal 

 spines back of the cervical suture are most of them but little smaller than the 

 rostral spine, are directed more upward than outward, and there are nearly as 

 many more additional smaller spines alternating with the larger. There is a 

 conspicuous additional spine in the middle of the gastric region, and numerous 

 additional small spines on other parts of the carapax. 



