CRUSTACEA OF THE MERGUI ARCHIPELAGO. 9 
1. DoctEsa HYBRIDA, Fabr. 
Inachus hybridus, Fabricius, Supplementum Entomologie systematice, 
Hafn. 1798, p. 355. 
Doclea hybrida, Milne-Edwards, Histoire Naturelle des Crustacés, t. 1. 
1834, p. 294. 
(Compared by me with the typical specimen of Fabricius, pre- 
served in the Museum of the University of Kiel.) 
One fine female specimen was collected at Sullivan Island. 
The length of the cephalothorax* measures about 35 millim., 
while the breadth amounts to 34 millim., the lateral spines being 
excluded. The cephalothorax, which appears nearly circular, 
has an extremely convex and semiglobular upper surface, which 
bears many dentiform tubercles ; the woolly down with which 
this species is covered is only observed in this specimen near the 
antero-lateral margins. The rostrum, which is a little broken 
off at the tip, is short, though not shorter than that of Doclea 
ovis, as figured in Milue-Edwards’s ‘ Regne Animal de Cuvier,’ 
plate 33; it is 6 millim. long from the tip to a transverse line 
which unites the two internal angles of the fissures that are 
found in the upper margins of the orbits, while this transverse 
line, which I regard as the base of the rostrum, is itself 9 millim. 
long. The antero-lateral margins are armed with four rather 
short though acute spines; the second spine is the smallest, 
the third is a little longer than the first, and the last spine is still 
somewhat longer and larger than the third, measuring 34 millim., 
directed transversely outward (not forward), and being exactly 
equidistant from the external orbital angle and the base of 
the spine with which the posterior margin of the carapace is 
armed. The latter spine is very short, measuring only 2 millim., 
so that it is as long as the third antero-lateral spine and directed 
horizontally backwards. The interregional grooves on the upper 
surface of the cephalothorax are rather strongly marked, so that 
the regions are very distinct. The upper surface of the cephalo- 
thorax is armed with many short, rather obtuse, dentiform 
tubercles, which are arranged in the following manner :—First, 
seven tubercles of equal size are placed in a longitudinal row on 
the median line of the upper surface, viz. five on the gastric, one on 
the cardiac, and one on the anterior part of the intestinal region. 
* Longitudinal distance from the posterior margin to a line which unites 
the eyes, so that the rostrum and the spine of the posterior margin are 
excluded. 
