2 76 CEYLON PEARL OYSTER REPORT. 



external margin of the furcal rami. Three females of this species were found in the 

 washings from the Muttuvaratu pearl oysters. 



Idya furcata (Baird). 



' A common British littoral species. Occurred at 7 stations from the English Channel 

 through the Mediterranean and Gulf of Suez to the Red Sea. 



Idya longicornis, T. Scott. 



Found in the general washings from Ceylon Invertehrates. Previously known only 

 from British waters. 



Pseudanthessius gracilis, Claus Plate XIV., figs. 19 to 23. 



One specimen was found in the general washings of the Ceylon Invertehrata 

 ohtained ahout the pearl banks. We give some additional figures of this species. 



Pseudanthessius maximus, n. sp. Plate XIV., figs. 1 to 11. 



Length, female 3' 5 millims. ; male 2 - 7 millims. 



Cephalothorax 6- jointed, the lateral spaces between the joints giving it a coarsely 

 pinnatifid appearance. Abdomen of female 4-jointed, male 5-jointed, the 1st segment 

 in the male being much longer and wider than any of the others. 



Anterior antennae 7 -jointed, each joint bearing several short spinous setae, and the 



. , , . . . . ,. 1. 2. 3. 4. 5. 6. 7. 



proportional lengths being: as follows : nn . ^ - 



Posterior antennae 4-jointed, the 3rd joint much the smallest ; the 4th bears a stout 

 blunt hooked spine. Mandible is produced apically into a long recurved spine with 

 toothed edges, also a smaller toothed spine, and toothed edge. The pal}) is short, 

 armed with three apical spines and a lateral one. First maxilliped has a stout basal 

 joint, with an outer joint extended into 2 curved hairy spines. Second maxilliped of 

 female has an oval middle joint terminating in a short claw ; that of the male is a 

 strong grasping hand, the terminal claw long and stout. 



First pair of natatory legs has both branches 3-jointed, the outer one armed with 

 serrated lanceolate spines ; both branches have numerous plumose setae. Fourth pair 

 2-branched ; the outer one 3-jointed, armed with short ovate serrated spines, the 

 inner branch consists of 1 long joint gradually widening to the apex ; the lateral 

 posterior edges are produced into spines, between which are 2 terminal plumose setae. 

 The 5th pair consist each of a long curved joint with 3 terminal plumose spines. 

 Furcal rami about 3 times as long as broad, slightly tapering to apex. 



Several males and females were taken by surface tow-net in Galle harbour. 



This species is easily distinguished by its large size, by the mandible and posterior 

 antennae, and by the 4th and "5th pair of natatory legs. 



