1 1 



and horizontal; it appears therefore rather incorrect to describe the carapace of this and other 

 allied species as "depressed", as we read in the "Catalogue of the Indian Deep-Sea Crustacea". 

 As regards the armature of the mid-dorsal carina, this species fully agrees with Siereom. phos- 

 phorus. Between the two rostral teeth and the cervical groove the carina carries four spines, 

 the penultimate of which is doublé; the two rostral teeth, which are directed upward and 

 somewhat forward, are in this specimen coalesced for three fourth parts of their length. The 

 three pairs of juxtaposed spines, posterior to the cervical groove, agree, as regards their 

 position and size, with those of Siereom. pkosphorus, the two spines of the posterior pair being 

 farther distant from one another than the rest. 



The lateral borders of the carapace present exactly the same armature in all 

 the 18 specimens of this collection, so that we may conclude that the number of spines 

 on their three divisions is characteristic. The antenor division is invariably armed with 

 5 spin es, including the spine at the antero-lateral angle, which is slightly curved inward and 

 a little longer than the four others. The middle division of the lateral border carries 3 s p i n e s 

 and the posterior, that is somewhat longer than the two other ones taken together, constantly 

 with 9: except the first, which is somewhat larger, the eight other spines, with which the 

 lateral border of the branchial region is armed, are of the same size and equidistant, though 

 we must remark that the last spine is twice as far distant trom the posterior extremity of the 

 border as from the S th or penultimate. The notch that separates the anterior and the middle 

 division of the lateral border from one another, is a little larger and deeper than that of the 

 cervical groove. There is also a longitudinal row of spines on the branchial region extending 

 from the posterior margin till near the cervical groove; it is twice as far distant from the 

 mid-dorsal carina as from the lateral border and is slightly undulate, so that it appears, 

 just behind the middle, somewhat farther distant from the lateral border than at its 

 extremities. This row is armed with 13 spines, which are somewhat smaller than those of 

 the lateral border and equidistant, except the two last ones that are farther distant from one 

 another. In Stereom. phosphorus, however, this sublateral ridge carries only 7 spines and it 

 runs quite straight in the quoted figure 2 of the "Illustrations" ; the lateral borders are armed, 

 in this species, "with 6 (rarely 7) + 3 (rarely 4) spines in front of the cervical groove, and 6 

 or 7 behind it". Like in Stereom. phosphorus, one observes five or six small spines on the 

 anterior half of the branchial regions, just outside the oblique furrow defining the cardiac region 

 and one or two more are visible somewhat farther backward near the sublateral ridge. Stereom. 

 trispinosa carries likewise the 6 spines on the anterior portion of the carapace, that are found 

 in Stereom. phosphorus, on each side of the median carina, viz. three in an oblique row running 

 from the orbital notch backward and inward, one at the bifurcation of the cervical groove and 

 two between it and the former. In the adult female the posterior border of the carapace carries 

 a few minute sharp granules, though it cannot be said to be spinulose. The ventral sidewalls 

 are minutely granular and somewhat hairy ; the two oblique ridges are spinulose, the lower 

 armed with about 50 spinules, that somewhat diminish in size near both extremities. 



The carapace, measured in the middle line, appears two-thirds of a telson-length shorter 

 than the abdomen. 



