SURFACE COPEPODA OF THE OTTLF OF MANNAR. 237 



remarking on the frequency with which these males are 

 associated with the females of the preceding species, and in 

 neither case have any corresponding members of the opposite 

 sex been obtained. The male, P. danse, as described, is 

 obviously not the same as the present species, but it is possible 

 that the variety of the female, as described by Thompson & 

 Scott, is in reality a different species, and I am inclined to 

 regard it as the female of P. investigatoris . There is a very 

 close similarity in the general structure, and especially is this 

 seen in the relative lengths of the antennal jomts in the two 

 forms. I give below the proportional lengths of the joints in 

 the antenna of P. danse var. ceylonica ($), and those of the 

 unaltered antenna of P. investigatoris {^). 



Segments : 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 

 P. danse ; 



vai\ ceijlonica. '^ . . 95 71 16 17 20 22 20 20 27 23 22 38 



P. investi- 

 gatoris, ^ .. 98 71 16 16 18 20 18 18 25 20 20 35 



Segments • 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 



P. danse ; 



var. ceylonica, '^. . 38 42 47 61 61 66 71 49 47 50 34 43 



P. investi- 

 gatoris, (J .. 34 34 44 59 60 70 76 56 56 56 40 48 



It is obvious that there is a fairly close resemblance between 

 these two forms, and I am inchned to beheve that the form 

 described by Thompson & Scott as P. danse var. ceylonica is 

 in reahty not a variety of Giesbrecht's species, but the female 

 of P. investigatoris. 



PoNTELLA FERA, Dana. 



Pontella fera, Giesbrecht, 1889, p. 28. 



Giesbrecht, 1891, p. 282. 



A. Scott, 1902, p. 408. 



Thompson & Scott, 1903, p. 252. 



Wolfenden, 1905, p. 1021. 



A. Scott, 1909, p. 159. 



Although recorded from various parts of the Indian Ocean 

 and its offshoots, this species would appear to be by no means 

 2 I 6(10)13 



