432 On Ascension-Island Zoology. 
CRUSTACEA. 
The crabs are few and unimportant. They include a very 
small male specimen that I refer to Xanthodes melanodactylus, 
A. M.-Edw., whose occurrence at Ascension I have already re- 
corded *, three specimens of Pachygrapsus transversus, Gibbes, 
three of 'Letolophus planissimus (Herbst), a small specimen of 
the anomurous genus Petrolisthes that is very probably referable 
to the West-Indian P. armatus, Gibbes, since it agrees with 
Gibbes’s description in nearly all particulars, having, however, 
the spines on the upper margin of the third joints of the am- 
bulatory legs very small and almost concealed by the stiff 
setee and slenderer pinnated hairs with which the margins are 
clothed; the carapace and legs are covered with a close, 
thick, whitish pubescence; but there are scarcely any traces 
of its disposition in transverse lines except on the merus 
joints of the chelipedes; the carapace and legs are very 
prettily mottled with pink. Length of carapace nearly 23 lines 
(5 millim.). 
Besides the above there are in the collection two small 
specimens of a crabin a larval (DMegalops) stage of develop- 
ment, which cannot be certainly identified with any known 
species. 
To render this brief account of the Crustacean fauna of this 
isolated rock the more complete, I subjoin the description of a 
species in the British-Museum collection which is apparently 
undescribed. 
Pseudozius Mellissc, sp. n. 
In this handsome species the carapace is transverse, much 
broader than long, its surface punctulated, the punctulations 
numerous and crowded in front, sparser posteriorly, and nearly 
obsolete near the postero-lateral and posterior margins. Some 
larger pits occur here and there near the antero-lateral margins 5 
and the upper margins of the carpus and hand of the cheli- 
pedes are also punctulated. The front is four-lobed ; the two 
median lobes are prominent and rounded and separated by a 
well-defined median notch; the outer lobes (or inner orbital 
angles) very little prominent, and separated from the median 
lobes only by a rather shallow sinus. The antero-lateral mar- 
gins are longer than the postero-lateral margins, and are defined 
along the greater part of their length by an obliquely striated 
entire line or crest, after which follow, at the broadest part of 
the carapace, two small but distinctly-defined teeth. All the 
joints of the postabdomen are distinct in both sexes. ‘The 
* Vide Ann, & Mag. Nat. Hist. (ser. 5) viii. p. 215 (1881). 
