II Kill ICR CRL'STACKA OF 



NEW YORK CITY 



and dredgers. In these localities they appear to be fond of living 

 w ithin the dead shells of oysters which are slightly gaping- and filled 

 with mud, but they will take up their abode in almost any crevice 

 they can find. The red sponge, M i c r o c i o n a prolifera, 

 is frequently filled with small specimens. They are not at all active 

 in their movements, and probably remain for long periods in their 

 retreats, waiting for their food to come to them. When disturbed 

 however, they try to conceal themselves under the nearest rock or 

 in the mud. 



P . depressus and s a y i are very similar and are frequently 

 found together and may be distinguished from h a r r i s i i by their 

 larger size and heavier build, and in having the fingers or ends of 

 the larger claws black. 



The two species differ in the form of the carapace, an adult speci- 

 ment of P. sayi measuring about 17 mm in length by 22.5 mm 

 in breadth, a ratio of 1 to 1.34. P. depressus is broader in 

 proportion to its length, a New York specimen measuring 26.5 mm 

 by 18 mm, a ratio of 1 to 1.47. The carapace of sayi is also 

 more swollen and convex than that of d epressus, and the front 

 is arcuate in the former and nearly straight in the latter. The 

 terminal segment of the abdomen of the male is in sayi [fig.ioe] 

 broadly triangular and wider than long, while in depressu s 

 [fig. iod] it is more nearly an equilateral triangle. 



P . h a r r i s i i is found near high water mark and is rarer than 

 the others. Adults measure 14 by 11 mm, and the carapace has 

 more of a quadrilateral form. The large claws are also more slender 

 and are of a lighter color, and the walking legs are slender and com- 

 pressed. The transverse lines on the carapace are more prominent 

 than in the others. 



Sayi and depressus are very common along the shores 

 wherever there are mud and stones, and may always be found there. 

 H a r r i s i i has been taken under stones near Flushing and at the 

 Fresh Kills on Staten Island. 



