56 CEYLON PEARL OYSTER REPORT. 



about as long as the third and fourth combined, the third being much longer than 

 the fourth, nearly as long as the sixth, which is slightly shorter than the fifth. The 

 finger is less than half as long as the sixth joint ; it curves to a sharp apical point, 

 which is overhung by an unguisdike sjjine, while on the concave margin of the finger 

 there is a small spine. The peraeopods differ little in character from the second 

 gnathopods, except that the second joint is less elongated and the third joint is more 

 nearly subequal in length to the sixth. To the first and second gnathopods and first 

 and second perreopods in one of the specimens four pairs of marsupial plates were 

 attached, the third pair being the largest, but the fourth also of considerable size. 

 In dissection of the pleon there came away a linear ring, which, perhajjs, represents a 

 degraded first pleon segment. Dorsally two such segments are indicated.* A small 

 unpaired plate, square above and triangular below, without any trace of longitudinal 

 or other suture, must be regarded as representing the first pair of pleopods.f The 

 second pleopods are wanting, as in other females of this tribe. The third pleopods 

 form a very large pair of biramose appendages, the peduncle small, the inner ramus 

 branchial, with three or four seta? on the narrow apex, the outer ramus of great size, 

 with slightly oblique transverse suture below the middle, but starting just above the 

 apex of the inner ramus. The fourth pair are biramose, and have the oval inner 

 branchial ramus much broader and not shorter than the outer ramus, which shows a 

 transverse suture above the middle and has the tapering lower division fringed with 

 several long setae. In the fifth pair each pleopod consists of a single branchial ramus, 

 possibly representing a coalescence of two rami, the outer margin raised and distally 

 fringed with setae.j 



The uropods are inserted a little within the distal margin of the telsonic segment, 

 separated by the convexity which may he considered an equivalent of the actual 

 telson. The peduncle is rather stout, shorter than the rami, of which the inner is the 

 larger, both being well furnished with tufts of long setae on sides and apex. 



Description of the uropods and the complete second antennae is based on a specimen 

 of the same dimensions as the one figured, but which did not come to light till after 

 the less complete example had been figured. This second specimen was straight, but 

 a third, rather smaller specimen with it had a distortion similar to that shown in the 

 plate. 



Length 4'5 millims., breadth 1'5 millims. 



Locality : Reef, Galle, with Ascidians ; and Coral banks, Gulf of Manaar. 



* For the genus at large Hansen says, " two rudimentary segments are observed in front of the large 

 abdominal shield" (loc. cit., p. 304). 



t Haswell (loc. cit., p. 1010) says: "The bases of the first pair of abdominal appendages are 

 covered in both cases by a broad plate, with a bifid apex attached to the posterior border of the last 

 thoracic segment." By "both cases" no doubt the two sexes are intended, and "the first pair of 

 abdominal appendages " are really the third pair of pleopods. 



X Hansen in his character of the family says in regard to the pleopods, "fifth pair with only one 

 ramus, in all probability the exopod " (loc. cit., p. 315). 



