114 PERCY SLADEN TRUST EXPEDITION 



30 fathoms. The young were all in the epicaridian stage, in which the fifth pair of 

 peraeopods is still undeveloped. 



Gen. TRAPEZICEPON, Bonnier. 



1900. Trapezicepon, Bonnier, Les Bopyridae, p. 269. 



This genus is distinguished by its author from Cancricepon and Grapsicepon by 

 the absence of the medio-dorsal bosses on the hinder peraeon segments, and from 

 Portunicepon by the rudimentary condition of the inner branches of the pleopods, in 



the adult female. 



All the three genera were instituted by Giard and Bonnier in 1887, Portunicepon 

 being evidently a synonym of Ergyne, Risso, 1816. This last has the medio-dorsal bosses, 

 and the other two genera have the rudimentary inner branches of the pleopods, so that 

 the differential characters of Trapezicepon might well have been considered as of specific 

 rather than generic value. The four genera may be tabulated as follows : 

 ( Without medio-dorsal bosses on the peraeon. Trapezicepon. 

 \ With medio-dorsal bosses on the peraeon. 2. 



Inner branches of pleopods not rudimentary. Ergyne. 



Inner branches of pleopods rudimentary. 



Last four segments of peraeon with medio-dorsal bosses. Cancricepon. 



Only last two segments of peraeon with medio-dorsal bosses. Grapsicepon. 



It may be added that in Ergyne one species has the last three, and a second the 

 last two peraeon segments raised into median processes. 



30. Trapezicepon amicorum (Giard and Bonnier). (Plate 11b.) 



1888. Grapsicepon amicorum, Giard and Bonnier, Compt. Rend. Acad. Sciences, 



July 2, p. 2. 



1900. Trapezicepon amicorum, Bonnier, Les Bopyridae, p. 269, pi. 10. 



The present specimen agrees in general appearance with that figured and described 

 by Bonnier, but differs in some details. The inner branch of the pleopods is not apically 

 pointed but obtuse in the female, and the uropods are less elongate and with little 

 approach to digitation. In the male the medio-ventral tubercle could only be dis- 

 tinguished on the first three peraeon segments, instead of occurring plainly on each 

 segment of the peraeon and the first of the pleon. 



The length of the female was only a little over 2 mm., instead of 3 mm. 



The host was not Trapezia cymodoce (Herbst), but Actumnus tomentosus, Dana, $, 

 as identified by Miss M. J. Rathbun. Position of parasite in left branchial cavity of host. 



Locality. Amirante, 34 fathoms. 



As I was withdrawing the specimen from the tube, there fell from its well-developed 

 marsupium what I supposed to be a mass of eggs, but it proved to be a bladder-like 

 organism, showing no actual segmentation and no appendages unless a minute process 

 might pass for one. It was of a size to fairly well fill the marsupium of its host. It 

 is reminiscent of the species Cyproniscus cypridince, Sara, and the genus Asconiscus, 



