40 



Epistome broad, on an oblique plane, separated from the palate by a deep 

 vertical wall. Merus of external maxillipeds obovate, narrower than the ischium, 

 somewhat produced beyond the articulation — near the antero-internal angle — 

 of the palp. 



Chelipeds short. Legs slender, very long, ending in filamentous dactyli. 



This genus is very closely allied to Achseus. 



Physacliceus ctenurus, Alcock. 



Physachwus ctenurus, Alcock, J. A. S. B., Vol. LXIV. pt. 2, 1895, p. 175, pi. iii. figs. 2, 2a.h: 111. Zool. 

 R. I. M. S. Investigator, Crnst. pi. xviii. figs. 1, la-h. 



Carapace sub-triangular, globosely inflated, with all the regions, except the 

 cardiac, tumid and fairly well delimited, and with a strong post-ocular constric- 

 tion, beneath which there is an almost vertical descent to the mouth. 



The rostrum, which is small, consists of two narrow, slightly divergent, 

 hollow teeth, to either apex of which the distal end of the otherwise perfectly 

 free basal joint of the corresponding antennary peduncle is fused. 



Two large erect procurved spines occur in the middle line of the carapace ; 

 one on the posterior part of the gastric region, the other behind the cardiac 

 region : on either side of the former, but in a plane anterior to it, there may 

 sometimes be a spinule. 



In both sexes the abdomen consists of 5 pieces and is bluntly but strongly 

 carinated down the middle line. The carina in the case of the male ends on the 

 6th tergum in a huge recurved spine : in the female instead of a spine there is 

 a transverse row of four spinules, and sometimes also a tubercle or a second 

 transverse row of spinules. 



The eyestalks are very small, and are rigidly fixed at right angles to the 

 rostrum : the corneiB are almost devoid of pigment. There are no orbits or 

 orbital spines. 



The antennae are distinctly exposed from their base, and are half as long 

 again as the entire carapace, between one-third and two- fifths of their extent 

 being formed by the slender peduncle. The basal joint is slender and almost 

 cylindrical : it is quite free from neighbouring parts, except at the distal end, 

 which is fused with the tip of the rostrum. The flagella are fringed with long 

 hairs. 



The antennules are large, and fold longitudinally within the hollow teeth 

 of the rostrum. 



The chelipeds in the adult male are considerably more than 1^ times the 

 total length of the carapace and are considerably stouter than the legs, while in 

 the advilt female they are considerably less than li times the length of the 



