288 THE VOYAGE OE H.M.S. CHALLENGER. 
A female, probably adult, was obtained off tlie South Australian Coast, in 2 to 10 
fathoms, in April 1874. 
The nearest ally to this species with which I am acquainted is Calappa loplios 
(Herbst), from which Calappa depressa is distinguished by] the more depressed and 
tuberculated carapace, with less strongly-toothed lateral expansions, the more distinctly 
granulated chelipedes, &cd 
Young specimens of Calappa hepatica may be distinguished from Calappa depressa 
by their broader carapace, with less deeply emarginate front. 
Paracyclois, n. gen. 
Carapace about as long as broad, and moderately convex ; front narrow and trilobated ; 
the median lobe rounded and much broader than the lateral lobes. No lateral epi- 
branchial spine or tooth ; the antero-lateral margins are regularly arcuated and entire ; 
there is in the middle of each of the postero-lateral margins a strongly spiniferous lobe 
(the rudiment of the postero-lateral clypeiform prolongations of the carapace which are 
fully developed in Calappa). The subhepatic regions of the carapace are concave ; the 
channel thus formed communicating with the antennary region (and thereby with the 
buccal cavity) by a notch situated between it and the inferior wall of the orbit. Post- 
abdominal segments distinct. Eye-peduncles short, robust, closely encased in the oval 
orbits. Antennules obliquely plicate. Antennae with a quadrate basal joint, which does 
not reach the frontal margin, and a very short flagellum. Outer maxillipedes with the 
ischium longer than broad and longer than the merus, which is distally truncated, with 
the antero-internal angle very distinctly notched ; the following joints are exposed as in 
Calappa ; the exognath is slender, straight, and narrows slightly to its distal extremity, 
which does not reach the antero-external angle of the merus of the enclognath. Cheli- 
pedes and ambulatory legs as in Calappa and Cryptosoma, and the description of these 
limbs in Calappa applies to Paracyclois. 
This remarkable type apparently connects the genera Cryptosoma and Platymera 
with Calappa through such forms as Calappa ( Callus ) gallus (Herbst). As in these 
genera the merus of the outer maxillipedes is distally truncated, and bears the next joint 
at its antero-internal angle, which is prolonged in the form of a lobe or tooth, but Para- 
cyclois is distinguished from the first two of the above mentioned genera by the absence 
of any lateral spine on the margin of the carapace, and the broader basal antennal joint, 
and from Calappa i by the absence of the clypeiform prolongations of the carapace, which 
are represented by a slight protuberance of the postero-lateral margins in Paracyclois, 
which protuberance bears several strong spines. 
1 There are in the British Museum collection two small specimens of this species without special indication of 
locality, collected in the Voyage of H.M.S. “ Samarang.” All the specimens I have examined are of small size. 
