360 DE. W. T. CALMAN ON NEW OE EAEE 



somites, the much feebler serrations on the lower margin of the carapace, the shorter 

 posterior legs and exopod of the uropods, and in many other details. It also differs 

 from all other Cumacea, with the exception of K reptans described above, in having 

 no exopods on the first and second pairs of legs. 



Occurrence.— GnM of Siam, " Koh Kam, 5-10 fathoms, 2/00," " Koh Kahdat, 

 4-5 fathoms, 16/2/00," " BetAveen Koh Mesan and Cape Liant, 5-8 fathoms, 8/2/00," 

 "North of Koh Mesan, 10-15 fathoms, 15/2/00." Th. Mortensen Coll., Copenhagen 

 Museum. Co-types in British Museum. 



Nannastacus agnatus, sp. n. (Plate XXXIV. figs. 12 & 13.) 



Description of adult Female. — Total length 1'3 mm. 



Eesembling the specimens of N. tardus very closely, but having well-developed 

 exopods on the legs of the first and second pairs. The basis of the first legs is a little 

 shorter, but is shaped as in that species ; the basis of the second legs is a little 

 longer; the posterior legs appear to be slightly stouter and shorter. The last somite 

 is distinctly shorter and the peduncle of the uropods is more than half its length. 



Remarks. — Apart from the presence of exopods on the first two pairs of legs, I have 

 not been successful in finding any characters other than those mentioned above to 

 differentiate this species from N. tardus. The possibility suggests itself, therefore, 

 even more strongly than in the analogous case of N. reptans and N. minor, that we 

 have to do here with a single species in which the exopods may be lost (1) by accident, 

 (2) as a matter of individual variation, or (3) normally in the course of the breeding- 

 period. The analogy of other Cumacea makes the first of these very improbable ; as 

 regards the third it is to be noted that both forms are represented by ovigerous 

 females, and that the specimens of N. tardus are on the whole, a little longer than 

 those of N. agnatus. I do not think that any importance can be attached to the fact 

 that, except in one case, the two forms occurred together in the same gatherings, and 

 in the absence of conclusive evidence that they belong to a single species, it seems 

 convenient to assign specific names to both. 



Occurrence. — Gulf of Siam, " Koh Kam, 5-10 fathoms, 2/00," " Koh Kahdat, 

 4-5 fathoms, 16/2/00," " Between Koh Mesan and Cape Liant, 6-8 fathoms, 

 8/2/00," "North of Koh Mesan, 10-15 fathoms, 2/00." Th. Mortensen Coll., 

 Copenhagen Museum. Co-types in British Museum. 



ScHtzoTEEMA, gen-, nov. 



Carapace more or less depressed, not overhanging the anterior free somites ; lateral 

 plates of pseudorostrum not meeting in front of head, exhalent respiratory orifices 

 paired and widely separated from each other; third maxillipeds and first two pairs of 

 legs with exopods in female : other characters as in Nannastacus. 



