24(5 CEYLON PEARL OYSTER REPORT. 



Anterior antennas 25-jointed, nearly equalling in length the cephalothorax. The 

 proportional lengths of the joints are as follows : 



1. 2. 3. 4. 5. G. 7. 8. 9. 10. 11. 12. 13. 14.J5. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 

 15. 20. 7. 7. 7. 7. 7. 7. 7. 7. 7. 7. 8. 8. 8. 9. 8. 8. 8.' 7. 7. 11. 17. 21. 20. 



Posterior antennas 2-branched, the outer branch consisting of 2 joints, the inner 

 of 8, the 2 basal and the apical joints being each about double the length of the 

 intermediate ones. Mandible broad with 9 or 10 small teeth, palp 2-branched, one 

 branch having 2, the other 4 joints. Maxilla well developed, inner branch composed 

 of 2 large setiferous digits. First and second maxillipeds similar to those of the 

 Calanidse. 



Natatory legs 1 to 4 with outer and inner branches all 3-jointed, the lateral and 

 terminal spines destitute of serrations and hairs. The inner branch of 5th pair is 

 2-jointed ; the outer branch 3-jointed, bearing lanceolate spines with serrated edges ; 

 the 3rd joint is attached to the centre of the 2nd joint. 



Two specimens, both females, were found in the Muttuvaratu pearl-oyster washings. 



This, the only known representative of the genus Iiidgewayia, is easily recognised 

 by the inner branch of the posterior antennas, by the hooks on the last thoracic and 

 genital segments, and by the 5th pair of natatory legs. 



Phaenna spinifera, Claus. 

 Occurred at 3 stations, near Gibraltar, in the Red Sea, and in the Indian Ocean. 



Famu.y : CENTKOPAGID^E. 



Centropages chierchiae, Giesbr. 



Occurred at 5 stations, near Gibraltar, in the Indian Ocean, and about the Cheval 

 Paar and other pearl banks, ( leylon. Not previously reported from the Indian Ocean. 



Centropages typicus, Kroyer. 



A well-known northern species, common around the British coasts. Occurred at 

 3 stations in the Mediterranean. 



Centropages violaceus, Glaus. 

 Found at 11 stations, extending from the Mediterranean to the lied Sea, and 

 throughout the Indian Ocean. 



Centropages furcatus (Dana). 



One of the commoner species of this genus. Occurred at 29 stations, from the lied 

 Sea throughout the Indian Ocean. 



Centropages elongatus, Giesbr. 

 Found at 8 stations, from the Gulf of Suez throughout the Indian Ocean. 



