204 STALK-EYED CRUSTACEA. 



appendages of the last two thoracic segments are rarely preserved in their 

 inte'Tity. It would seem from the perfect specimens, that these appendages 

 are longer than represented by Bate, the hindmost pair being the longest of 

 all the legs, reaching forward to the distal end of the antennal scale. The 

 dactylus of this appendage is less than one half as long as the propodite, the 

 latter segment a little longer than the carpus. In Bate's diagnosis of the 

 genus it is said that the legs all bear small exopods that become rudimen- 

 tary posteriorly. No special mention of the exopods is made in his descrip- 

 tion of B. alius, neither are they shown in his figure of this species. In 

 the '•■ Albatross " specimens there are no exopods on any of the appendages 

 behind the third maxillipeds. In other respects these specimens agree so 

 closely with Bate's description and figure that I do not doubt that they 

 belong to the same species. 



Specimens from different stations vary to some extent in the degree of 

 induration of the integument. In all the examples, nevertheless, it is rather 

 soft and membranaceous in its texture. 



The terminal segment of the third maxillipeds in this species, as well 

 as in the following [B. taimeri), is short, broad, curved, and compressed. In 

 the female the external margin of this segment is regularly convex. In the 

 males, this segment exhibits two forms : one like that of the female, the 

 other conspicuously different, the external margin being produced into a 

 large rounded tooth or lobe. In the latter form the whole segment assumes 

 a bilobed outline as shown on Plate H., Fig. 1^ This difference in the form 

 of the dactylus of the third maxillipeds in the males is accompanied by a 

 difference in the petasma, or sexual appendage of the first abdominal limbs. 

 In those males which have the third maxillipedal dactylus of the form first 

 described the petasma is comparatively small, feeble, and free from calcareous 

 deposit. In the males with bilobed third maxillipedal dactylus the petasma 

 is larger, more perfectly finished, and stiffened by calcareous matter. It is 

 clear that the latter form of the male is a state equipped for repi-oduction 

 (see foot-note on page 74). 



Spence Bate, in his generic diagnoses of BcMcsicymus and Gcmmdas, says 

 that in the former genus the dactylus of the third maxillipeds is cylindrical 

 and sharp. But the figures of most of his species of Bcnthrsici/nms show 

 a broad compressed dactylus like that seen in tlie species in the " Alba- 

 tross " collection. Professor Smith's genus BeiUhoecetes* is synonymous with 

 BcntJiesici/mus. 



* Ann. Rep. U, S. Fish Comni. for 1882, p. 3'Jl, 1884. 



