324 
THE VOYAGE OF H.M.S. CHALLENGER. 
Leucosia haswelli, n. sp. (PI. XXVII. fig. 2). 
The carapace is shaped nearly as in Leucosia reticulata, Miers, to which this species 
is nearly allied, i.e., it is rounded above, convex, smooth and polished, somewhat rhom- 
boidal, with a prominent front whose anterior margin is straight or very obscurely 
sinuated, not dentated or emarginatecl ; its upper surface is covered with scattered 
punctulations which are most abundant on the anterior part ; its sides are bordered by 
a granulated line which extends along the antero-lateral margins and terminates on the 
postero-lateral margins, just above the bases of the first ambulatory legs ; the posterior 
margin also is defined by a line of smaller granules, which is prolonged along the sides of 
the body above the bases of the ambulatory legs, and terminates behind the chelipedes. 
The thoracic sinus is shaped as in Leucosia reticulata, and, as in that species, contains 
several flattened tubercles. The eyes, antennte, and maxillipedes present nothing remark- 
able ; the rounded prominence which is observable on the ischium of the outer maxilli- 
pedes in Leucosia reticulata is not developed, or is very obscurely indicated, in Leucosia 
haswelli. As in Leucosia reticulata, the merus of the chelipedes is tuberculated in its 
proximal half, and the tubercles are, as in that species, crowded at the base and extend along 
the anterior and posterior margins to the distal extremity ; the palm too is compressed, 
granulated on its inner, and slightly carinated on its exterior margin, as in Leucosia 
reticulata. The ambulatory legs (as usual in the genus) are slender, feeble and com- 
pressed, with the penultimate joints carinated above. Coloration, greenish or yellowish, 
with a large spot of a darker green on the back of each branchial region, and with two 
white spots on each side of the gastric region ; the tubercles of the upper surface of the 
merus-joints of the chelipedes in one specimen are crimson-red ; the ambulatory legs in 
both are yellowish. 
The largest example (a sterile female) is somewhat distorted, and has the following 
dimensions : — 
?. 
Lines. 
Millims. 
Length of carapace and front, nearly .... 
12 
25 
Breadth of carapace (allowing for its distortion), nearly . 
11 
23 
Length of a chelipede, nearly ..... 
HI 
24 
Length of first ambulatory leg, ..... 
^1 
20 
Arafura Sea, south of New Guinea, in 28 fathoms, lat. 9° 59' 0" S., long. 139° 42' CCE. 
(Station 188), an adult female; Celebes Sea, in 10 fathoms, lat. G° 54' 0" N., long. 
122° 18' 0" E. (Station 212), a sterile female. 
This species in all of its characters nearly resembles Leucosia reticulata, Miers, 1 from 
West Australia, from which it is distinguished not only by the different disposition of 
the markings of the carapace, which more nearly resemble those of Leucosia pallida, 
1 Trans. Linn. Soc. Lond. (Zool.) ser. 2, vol. i. p. 237, pi. xxxviii. figs. 13-15, 1877. 
