22 CEYLON PEARL OYSTER REPORT. 



The upper lip appears to be rounded, membranaceous. The mandibles have the palp 

 planted near the base of the trunk, with the first joint nearly as long as the second, 

 the third not very short. The first maxillae are long and slender, the small apex 

 carrying three hooked spines and lour spinules. The second maxilla? are much broader 

 than the first, having the inner margin of the apex armed with three little hooks, 

 in addition to which a small, narrowly oval, movable inner plate is tipped with two 

 hooks. The maxillipeds have an irregularly rounded epipod, as wide as the second 

 joint, which is itself wide, elongate, and produced into a narrowly tapering process 

 tipped with two setules. The third joint is short, distinct, the fourth and fifth have 

 distinct outlines, but are, perhaps, only apically separate, the fifth carrying outward 

 curved spines at its apex, its outer margin forming a continuous curve with the 

 faintly separable sixth and seventh joints, which together have a free inner margin 

 tipped with two outward curving spines. As will be seen from the figures, this 

 accounl of the mouth organs in the male has been a little supplemented from the 

 mouth organs of another specimen possibly of a different sex. 



The first gnathopods have a few short finely plumose seta 3 along the front margin 

 of the rather narrow second joint, and the same garniture seems to occur on the 

 corresponding margin in the other limbs. The third joint is rather longer than the 

 fourth and carries a single spine at its front apex. The fourth joint has two stout 

 spines on the hind margin, the fifth is small, underriding the sixth, but not overlapped 

 in front by the fourth ; its spines like those of the hand are slight. The finger is 

 nearly as long as the hand, with setules marking the base of the nail. 



The second gnathopods are very similar to the first, but stronger and more spinose. 

 The third joint has a stout spine on the hind margin, and the fourth has four or five 

 such spines; the fifth joint does not underrkle the sixth. The first perseopod is of 

 nearly the same appearance. On the left side of the specimen each of these limbs 

 has, on the inner apex of the short fifth joint, an articulated obtuse process about 

 twice as long as it is broad, giving the limb a subchelate character. On the right 

 side of the specimen these processes are not present. Whether they are abnormal 

 growths on the left side or are accidentallv missing from the right I cannot deter- 

 mine.* The side-plates of the second gnathopods are round-ended. In the following 

 limbs they tend to become less and less obtuse and those of the fifth perreopods are 

 subacute, produced over the first segment of the pleon, of which, however, the angles 

 are free. 



In the last four pairs of pereeopods the third joint attains a considerable length, 

 this anil the three following joints being armed with numerous well developed spines, 

 of which a group on the hind apex of the fifth joint, though not very long, are 



* It is worth noting for comparison that Sars ('Crustacea of Norway,' vol. 2, p. CI) describes the three 

 anterior pairs of legs in JEga crenulata, Lutken, as "distinguished by a very conspicuous cultriform spine, 

 issuing from the end of the propodos, inside the base of the daetylus," and 'WliiTELEGriE (' Mem. Australian 

 .Museum,' iv., pt. 2, p. 233) describes a similar process on first peiwopods of his Mga ungnstata, 



