288 CEYLON PEARL OYSTER REPORT. 



pair extends slightly beyond the 2nd; the inner ramus very small, the outer almost 

 as long as the peduncle, curved, with a minute terminal joint, no spines or setae 

 (fig. 45. up. 3 ). Telson obtusely pointed. 



Length 2 millims. 



The peculiar gnathopods of this small species seem to indicate that a new genus 

 will be required for it when the male is found. 



Chevalia, n. gen. 

 Body laterally compressed. 



Head without a rostrum. 



Antennas subequal, the Upper with an appendage. 



Mandibles small ; palp long and slender, 3-jointed. 



First and 2nd maxillae as in Cerapus, but relatively smaller. 



Palp of the maxillipeds with the last joint blunt. 



First gnathopods slender, as in Garnmaropsis. 



Second gnathopods with large wrist and hand alike in both sexes. 



The last 3 pairs of peraeopods with the dactyli inverted, as in Cerapus. 



First and 2nd uropods with dissimilar rami ; 3rd with 2 well-developed rami. 



Telson, as in the Photidae. 



This curious genus is intermediate between the Photidae and the Corophiidae. It 

 resembles the former in the form of the body, head, antenna?, gnathopods, and telson ; 

 and.the latter in the inverted peraeopods and the dissimilar rami of the 1st and 2nd 

 uropods, though in the new genus the dissimilarity is greater. Notwithstanding 

 these points and the similarity of the 2nd gnathopods in the males and females, I 

 have placed this form under the Photkke as the family with which it has the greatest 

 affinity. 



Chevalia aviculse, n. sp. Plate VII., figs. 50, and Plate VIII., fig. 50). 



Pearl oyster washings, East Cheval and Muttuvaratu paars : about 20 specimens 



Body smooth, without dorsal spines or teeth ; much curved ; speckled with red. 



Head as long as the first 2 segments ; ocular lobe subangular, not very prominent. 



Eyes oval colourless in spirit. 



Segments of the mesosome increasing in length successively, the 7th twice as long 

 as the 1st. 



Pleon segments with a jjair of upright setae on their postero-dorsal margins ; the 

 epimere of the 3rd rounded behind and below. 



First 2 segments of the urus coalesced and subequal to the last pleon segment ; 

 3rd segment about half as long. 



Antennae about two-thirds of the length of the body, subequal in the female ; the 

 upper rather the longer in the male ; in the upper the 1st and 2nd joints are sub- 

 equal, about one-third longer than the 3rd; flagellum 7 -jointed ; appendage 1 -jointed, 

 as lung as the 1st joint of the flagellum. 



