6 CEYLON PEARL OYSTER REPORT. 



the determination of female and immature specimens in obscurity. In regard to the 

 uropods the outer branch seems to vary not only in different species but even in the 

 same species, being sometimes two-jointed and sometimes one-jointed. The inner 

 branch has always more than three joints. 



Leptochelia mirabilis, n. sp. Plate I. (B). 



While in many of its features resembling L. minuta, Dana, and L. forresti 

 (Stebbing), the present species is easily distinguishable from them both and from 

 L. rapax, Harger, by characters of the first and second antennae, of the first 

 gnathopods and the uropods, as well as by its much greater size. 



The cephalothorax has the front rather broadly angled, not reaching beyond the 

 eyes, the sides at first slightly concave, then considerably bulging. In the dorsal line 

 the free segments of the peraeon are successively longer to the antepenultimate, with 

 a slight successive decrease in the remaining two. The first five segments of the pleon 

 are subequally short, the telsonic segment equal to two of them combined, apically 

 angular. The pleon at the centre is slightly wider than the peraeon. 



The eyes are movably socketed, dark, composed of a few large lenses. 



The first antennae are once and two-thirds as long as the body, the first joint a 

 little swollen and bent at the base, about nine times as long as the third joint, the 

 more slender second being about eight times the third ; the flagellum of thirteen joints, 

 carrying sensory filaments, is between two and three times as long as the third joint. 



The second antennae are about one-fourth as long as the first, the fourth joint of 

 the peduncle longer than the three preceding joints combined and more than twice 

 as long as the fifth joint, which is a little shorter than the two-jointed needle-like 

 flagellum, not including its two or three long apical seta? attached to the minute 

 second joint. 



The first gnathopods are of very surprising length, being much more than twice as 

 long as the whole body of the animal, and while, considered in themselves, they are 

 very slender, on the other hand, when compared with the frame that carries them, 

 their stoutness becomes a matter for wonder. The basal joints are short, but the 

 three terminal joints are of enormous length. The pair are not symmetrical and both 

 members are damaged, so that exact measurements cannot be given. In the larger 

 one the slender, apically curved, movable finger is equal in length to the first joint of 

 the first antennas ; it is shorter than the trunk of the hand, which widens to the hinge 

 of the finger, and is produced to a long slender thumb or immovable finger, the apex 

 of which is broken. The existing jjortion of the antepenultimate joint is longer than 

 the trunk of the hand, and is narrower near the base than in the greater part of its 

 length. In the shorter member the hand widens more abruptly and shows a little 

 gap at the base of the fingers, the movable finger being sinuous, and having three 

 little tubercles on the inner margin near the base. 



Second gnathopods of quite insignificant size, agreeing in character with the first 



