140 
THE VOYAGE OF H.M.S. CHALLENGER. 
Adult ? . Lines. Millims. 
Length of carapace, nearly . . . . . . 6 12 
Breadth of carapace, about . . . . . . 7J 16 
In this species or well-marked variety the tubercles of the dorsal surface are stronger 
and more distinct than in the almost equally common Pliymodius ungulatus, and they 
are more or less distinctly granulated or rugose, not (as often in Pliymodius ungulatus ) 
simply punctulated ; the chelipedes have the palm and wrist very distinctly tuberculated, 
the tubercles becoming spinous in the younger animal, and the finger in the young is 
spinous at the base ; whereas in Pliymodius ungulatus, the chelipedes are smooth or but 
obscurely tuberculated, and the fingers are without spines at the base . 1 
B. Endostome longitudinally ridged (Eriphiidse, Dana) : — 
Eurytium, Stimpson. 
Eurytium, Stimpson, Ann. Lyc. Nat. Hist. New York, voL vii. p. 56, 1859. 
„ A. Milne Edwards, Crust, in Miss. Sci. au Mexique, pt. 5, p. 332, 1880. 
This genus can only be distinguished from Panopeus and Eurypanopeus by the 
broader transverse carapace, which is nearly smooth, not lobulated, on the dorsal 
surface, and in the typical species is convexly arcuated in a longitudinal, not a 
transverse direction. The ridges on the endostome or palate are distinct and well 
developed, and the ducts leading to the male copulatory appendages pass to them from 
the fifth joints of the ambulatory legs beneath the margin of the sternum ; a character 
in which, as Dr. Stimpson notes, this genus is related to the Ocypodoidea. 
Professor A. Milne Edwards, however, has shown that short sternal channels for the 
copulatory organs exist in certain species of Eurypanopeus, and I may add, that both in 
Panopeus and in Eurypanopeus, the ridges of the endostome or palate are occasionally 
partially developed. 
Only two species are referred by A. Milne Edwards to this genus, Eurytium limosum 
(Say), which occurs on the eastern coasts of the American continent from New York to 
Rio de Janeiro, and was obtained by the Challenger Expedition at Bermuda, and 
Eurytium affine ( Panopeus affinis, Streets and Kingsley), which is found on the Cali- 
fornian coast and is intermediate between this genus and Panopeus, having the ridges 
of the endostome well developed, but the carapace shaped nearly as in Panopeus and 
Eurypanopeus. 
1 In a large series of specimens of Pliymodius ungulatus, in the collection of the British Museum, I have observed 
only one or two specimens which approach Phymodius monticulosus in these characters. 
