178 PROCEEDINGS OF UNITED STATES XATIONAL MUSEUM. [1885. 



The third, fourth, fifth, and sixth somites of the pleon are dorsally 

 cariuated, and on the fourth and fifth the carina is divided by a narrow 

 and deep incision in the posterior margin, leaving an inconspicuous 

 tooth either side which does not project above the carina of the succeed- 

 ing somite. The sixth somite is strongly compressed and about once 

 and a half as long as high. The telson is considerably longer than the 

 sixth somite, rounded and obscurely sulcated above, regularly tapered, 

 and armed with a long spiniform j^rocess either side of the acute tip and 

 three ]>airs of movably articulated spines, of which the posterior are 

 much the larger, arise just in front of the lateral processes, and reach 

 beyond their tips. The lamellae of the uropods are shorter than the 

 telson, the outer is only slightly longer than the inner, its thickened 

 outer margin terminates a little way from the tip, and both are nar- 

 row and obtusely rounded distally. 



The appendages of the first pleopods of the male are exceedingly 

 complicated and very different on the two sides. The left appendage 

 is the more simple and consists of an irregularly longitudinally plicated 

 plate which projects proximally in a curved i)rocess beyond the right 

 appendage and to the right of the mesial line, and distally in an irreg- 

 ular narrow process. The right ai)pendage is enlarged distally and 

 divided into several irregularly curved j)rocesses projecting beyond the 

 left appendage and partially covered posteriorly by a thin spoon-shaped 

 lamella arising at their bases. 



I have seen a single male (from which the accomijanying measure- 

 ments were taken), collected, with P. constrictus, at Bermuda, by Prof. 

 G. Brown Goode, and several smaller specimens, both male and female, 

 in the museum of Yale College, collected in the Bay of Panama by Prof. 

 F. H. Bradley. 



Measurements in millimeters. 



Sex $ 



Length from tip of rostrum to tip of telsou 57. 



Leugtli of carapax includiug rostrum 19. 4 



Length of rostrum 9. 



Height of carapax 7.5 



Breadth of carapax 7.5 



Length of eye-stalk and eye 4.^8 



Greatest diameter of eye 4.0 



Length of antenna! scale 10. 



Breadth of antennal scale 3.4 



Length of first peraeopod 11. 5 



Length of carpus 2. 7 



Length of chela 2. 4 



Breadth of chela 0. 7 



Length of dactylus 1.3 



Length of second perseopod 13. b 



Length of cai'pus 4.7 



Length of chela 2. 7 



Breadth of chela 0. G 



Length of dactylus t 1'2 



