COPEPODA. 259 



edges. The 5th pair in this mid the following 3 species are also different from the type 

 of the genus, and instead of being 2-jointed, are composed of 1 joint only, which, 

 however, is obviously built up of 2 coalesced joints. Fig. 2 represents a smaller form, 

 not differing in details of structure, except in the absence of hook from abdomen. 



Several specimens were found in the washings from the Muttuvaratu jjearl oysters. 



At Professor Herdman's suggestion we dedicate this new species to Mr. E. F. 

 1M Thurn, the Lieutenant-Governor of Ceylon at the time of the investigations. 



Tegastes donnani, n. sp. — Plate IV", figs. 10 to 12. 



Length, female, 0"37 millim. ; male unknown. 



In appearance and structure this species very nearly resembles T. imthurni, the 

 7-jointed anterior antennas and the 5th natatory legs being the only important points 



of difference. 



^ jn „ . . J 1. 2. 3. 4. 5. 6. 7. 

 .Proportionate lenpths of antennary loints : 



1 b J ■' 26. 26. 12. 22. 4. 8. 7. 



Four specimens, all females, were found in the Muttuvaratu pearl oyster washings. 

 We name this species after Captain J. Don nan, C.M.G.. formerly Inspector of the 

 Ceylon Pearl Fisheries. 



Tegastes twynami, n. sp. — Plate IV., figs. 13 to 16. 



Length, female (P54 millim. ; male unknown. 



This species also resembles T. imthurni in detail, with the exception of the anterior 



antemne, the hand of the 2nd maxillipeds, and the 5th natatory legs. The anterior 



antennae are only 6-jointed, the proportionate lengths of the joints being as 



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



follows : 



13. 13. 10. 8. 5. 5. 



The inner concave edge of the hand in 2nd maxilliped is strongly pectinated and 

 has a round funnel-shaped protuberance with ciliated edge similar to that of 

 T. imthurni ; the terminal falcate claw is very stout. Fifth pair of natatory legs like 

 those of T. donnani, but larger. Two specimens, both females, were found in the 

 washings from the Muttuvaratu pearl oysters. 



The cuticle in the foregoing species is covered with minute circular dots, these are 

 also found on the basal joint of the fourth pair of legs, on the fifth pair and in a lesser 

 degree on the chela of the posterior maxillipeds. 



We name this species in honour of Sir William Twynam, who has long been 

 connected with the Ceylon Pearl Fisheries. 



Tegastes chalmersi, n. sp. — Plate IV., figs. 17 to 22. 



Length, female, 0"3 millim. ; male unknown. 



A much smaller form than any of the three preceding. Cephalothorax 5-jointed ; 

 length and breadth of 1st joint about equal. 



2 L 2 



