48 CEYLON PEARL OYSTER REPORT. 



the setas of the apical border elongate, and the masculine appendix of the second pair 

 forming a narrow stilet which reaches to the end of the ramus and carries two long 

 apical setas. 



The uropods are rounded above, widest below the middle, then rather rapidly 

 narrowed to the rami, of which the external is very small, acutely triangular, and 

 reaching to the apex of the pleon. The internal ramus is still smaller. Colour in 

 spirit a dull yellowish. 



Length 9 millims., apart from the antennae, the lower of which are nearly as long 

 as the body, about 8 "5 millims. 



Locality : Periya Paar, Gulf of Manaar. 



A specimen, 4 millims. long, delicately pink in colour, from East Cheval Paar, is no 

 doubt the young of this species. It has the first perason segment not marked off 

 from the head, the fourth segment very elongate and smooth. The flagellum of the 

 first antennae is armed about the apex with only three or four sensory filaments. 

 The fifth perasopods are still imperfectly articulated, very small, ending obtusely 

 without a nail. 



Another specimen, from East Cheval Paar, is only 3 millims. long, with the fifth 

 perasopods in a still more inchoate condition. Here, however, the fourth segment of 

 the perason is not especially elongate and shows traces of median and terminal 

 tuberculation. The colour is a delicate pink. Neither in this nor the other juvenile 

 specimen is there a tooth on the fourth joint of the lower antennas. 



The specific name is from the Greek d/i./3\i;s, blunt, and obpd, tail. Apart from 

 size and arrangement of tubercles, the distinguishing characters of this species depend 

 on the antennal tooth just mentioned, the decided groove between head and perason, 

 the solidarity of the pleon, and the extension of the uropods further back than 

 appears to be the case in any of the sj)ecies hitherto described. 



Tribe: ASELLOTA. 

 Family: JANIRID/E. 



Sars, when separating this family in 1897 from the Asellkke, incidentally men- 

 tioned Stenetrium as belonging to the latter. Miss Richardson, in 1902, without 

 comment transferred the genus to the newer division within the Asellota. It certainly 

 seems to conform in many important respects to the following definition which Sars 

 himself gives of the Janiridas : 



" General habitus that of the Asellidas, but the lateral parts of the cephalon always 

 laniellarly expanded. Eyes, when present, subdorsal. Superior antennas sometimes 

 well developed, with the flagellum multiarticulate, sometimes very small, with rudi- 

 mentary flagellum. Inferior antennas always longer than the superior, with the 

 peduncle six-articulate, and generally carrying a small accessory appendage (scale) 

 outside the third joint. Oral parts normal. Legs subequal in length, with the 

 dactylus generally bi- or tri-unguiculate ; first pair sometimes differing from the others 



