10 BULLETIN OF THE 



The chelipeds and ambulatory legs have about the same proportions as in the 

 larger specimen, but are armed with very numerous acute spines, many of 

 which are of large size. The spines upon the second somite of the abdomen 

 are more numerous, and the larger ones much longer and more slender than in 

 the larger specimen. 



The small specimens are all immature, with the carapax excluding the 

 rostrum and spines less than 13 mm. in length, and differ so much from the 

 adults that they might readily be mistaken for a distinct species. These small 

 specimens differ considerably in size, but are all essentially alike. The smallest 

 and most perfect one is from the U. S. Fish Commission dredgings off Martha's 

 Vineyard. In this specimen (PI. I. figs. 2, 2») the carapax excluding the 

 rostrum and spines is only 12.6 mm. in length and scarcely more than seven 

 tenths as broad as long, but all three of the rostral spines and several spines of 

 the carapax proper are more than half as long as the carapax. The spines are 

 much fewer in number than in either of the adult specimens, very slender and 

 acute, and those at the base of the rostrum are just about as large as the rostrum 

 itself. The gastric region is proportionally very much larger than in the adults, 

 but is high and separated from the cardiac region by a deep sulcus, as in them, 

 and is armed with six slender spines, — two pairs on the highest part of the 

 region, of which the anterior pair are almost as long as the rostrum, but the 

 posterior considerably shorter, and a still smaller lateral spine each side. 

 There are two pairs of slender spines on the anterior part of the cardiac region, 

 the anterior a little longer and the posterior a little shorter than the posterior 

 gastric spines. The single hepatic spine each side is nearly as long as the 

 rostrum. The external angler of the orbit projects forward in a long and slen- 

 der spine, back of which are two smaller spines on the antero-lateral margin. 

 There are about twelve slender spines on the lateral and posterior margin back 

 of the cerA'ical suture each side, but they are all small compared with the other 

 spines of the carapax and about half of them are inconspicuous, and above 

 these on either branchial region there are six much larger spines, of which two 

 near the middle of the region are as long as the posterior gastric, but the others 

 considerably shorter. 



The eye-stalks and eyes are small and proportionally but little larger than 

 in the adult, but there are two or three shaq) spines projecting in front over 

 the eye in place of some inconspicuous tubercles in the adults. The anten- 

 nulse, antennae, and the exposed parts of the oral appendages, are nearly as in 

 the adults. 



The chelipeds are nearly as unequal as in the adults, and are armed with 

 very much longer and more slender spines, several of those upon the distal part 

 of the merus and upon the carpus being longer than the carpus itself. The 

 ambulatory legs have about the same proportions as in the adults, but the 

 spines with which they are armed are fully as long as those upon the chelipeds, 

 the longer 'ones, as in the chelipeds, being upon the distal parts of the meri 

 and upon the carpi. 



The abdomen is symmetrical. The second somite is made up of three calci- 



