272 CEYLON PEARL OYSTER REPORT. 



the terminal spines are shorter and less tumid ; secondary joint small. Marginal 

 spines, with the exception of the inner sub-terminal one which is very strong, short 

 and slender. Abdomen less tumid than in D. latieaudata. 



Several specimens, all females, from the same locality as the foregoing species, from 

 which it is distinguished by the structure and proportional lengths of the joints of 

 the anterior antennas, and by the 1st and 5th legs. The two foregoing species 

 differ in the structure of their appendages, especially in the 1st legs, which have the 

 inner branch only 2-jointed, from the general type of Dactylophusia, and may some 

 time require a separate genus. 



Dactylophusia platysoma, n. sp. Plate XI., figs. 13 to 18. 



Length, female 0'62 millim. ; male unknown. 



In general appearance more like a Porcellidium than a Dactylophusia, and it is 

 only when the appendages are examined that it becomes clear that it is not a 

 Porcellidium; neither can it be said to be a typical Dactylophusia, though pro- 

 visionally referred to that genus. Anterior antenna moderately long and slender, 



. . . , , ,. ,. , . ., 1 - 2. 3. 4. 5. 6. 7. 8. 9. 



9-jomted ; the proportional lengths are : 13 18 10< 9 4 5 2 2> 4< 



Posterior antenna?, mandible and palp, maxilla and 1st maxillipeds nearly as in 

 D. tisboides ; 2nd maxillipeds elongate, with a strong terminal claw. First natatory 

 legs resembling those of D. tisboides ; 2nd, 3rd and 4th though generally like those 

 of Dactylophusia, are more slender than the corresponding legs of any member of the 

 genus known to us. The 5th feet have the primary joint large and foliaceous. The 

 extremity of the joint is fringed with fine hairs, amongst which are 3 prominent 

 setae ; secondary joint not distinctly separated from the primary one, with rounded 

 margins and furnished with 6 apical setse. Abdomen very flat, 4-jointed, furcal 

 rami short. 



Six females were found in the washings from the Muttuvaratu pearl oysters. 



Thalestris mysis, Claus. 

 Found in the Gulf of Suez and again at Cheval P.aar, Ceylon. 



Pseudothalestris imbricata, Brady Plate XL, figs. 19 to 24. 



This species was described from a single specimen (a male) in the Report on the 

 " Challenger " Copepoda by Professor Brady. No further specimens seem to have 

 been discovered until now. In the present collection a single female was found in 

 washings from the Muttuvaratu pearl oysters, which from its general resemblance in 

 structural detail we have concluded is the female of P. imbricata. 



Length, female 0'65 millim. 



In general agreement with the recently described species of this genus, it is more 

 like a small Westivoodia than a Thalestris. The outer branches of the 1st natatory 



