508 



THE VOYAGE OF H.M.S. CHALLENGER. 



The plecm is furnished with a strong dorsal ridge that runs down the median line in 

 an interrupted manner, breaking up on each somite and each division of the somite into 

 a longitudinal cusp. The first somite has a central cusp which traverses only the first 

 half of it, and is elevated into a strong laterally compressed tooth, that has its point 

 directed forwards. On each side there is another large laterally compressed cusp that is 

 directed upwards and outwards but does not override the anterior margin of the carapace. 

 The median ridge, which on each succeeding somite is interrupted in the centre by a 

 transverse furrow, is most marked and projecting on the posterior extremity of the fourth 

 somite. 



On the fifth somite the median ridge is also present, but it is here a less important 

 feature, and the transverse sulcus is also less conspicuous and divides the carina into an 

 anterior and a posterior portion ; the anterior commences at the anterior margin and ends 

 at the sulcus, and is laterally supported by an obliquely placed cusp ; the posterior begins 

 at this sulcus and continues on each side obliquely backwards and outwards to the posterior 

 margin of the somite, having a cusp between these. 



The sixth somite has the median ridge well developed, divided at the middle, and 

 projecting posteriorly into a sharp tooth that overhangs the telson. 



The lateral walls, or coxal plates attached to the several somites of the pleon, are 

 inferiorly and posteriorly produced to a strong tooth, excepting in the case of the first, 

 which, when the pleon is flexed on the pereion, is covered by that of the second somite. 

 The whole surface is coarsely granulated. 



The telson is sharp pointed and dorsally grooved ; at the anterior extremity of this 

 groove the median dorsal carina is represented by a small tooth, on each side of which a 

 strong slightly serrate ridge traverses the upper surface and meet at the pointed extremity ; 

 from the ridge the lateral walls are perpendicular. 



Habitat— Station 218, March 1, 1874; lat. 2° 33' S., long. 144° 4' E.; between 

 New Guinea and Admiralty Islands; depth, 1070 fathoms; bottom, blue mud; bottom 

 temperature, 36° # 4. Two specimens ; one male, one female. Trawled. 



