204 STALK-EYED CRUSTACEA. 
appendages of the last two thoracic segments are rarely preserved in their 
integrity. It would seem from the perfect specimens, that these appendages 
are longer than represented by Bate, the hindmost pair being tlie 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. altus, 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. danneri), 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 reproduction 
(see footnote on page 74). 
Spence Bate, in his generic diagnoses of Benthesicymus and Gennadas, 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 Benthesicymus show 
a broad compressed dactylus like that seen in the species in the “ Alba- 
tross”’ collection. Professor Smith’s genus Benthwectes * is synonymous with 
Benthesicymus. 
* Ann. Rep. U.S. Fish Comm. for 1882, p. 391, 1884. 
