412 CEYLON PEARL OYSTER REPORT. 



of Neptunus (Lwpocycloporus) ivhitei, except that the anterior gastric ridge of the latter 

 is not represented. 



In ovigerous female (c) and in adult male (a) the three posterior of the interdental 

 denticles are excessively rudimentary ; a character described by Alcock for the young 

 (i.e., the absence of these denticles) tends thus to survive in the adult. 



Lupocyclus strigosus, Alcock, 1899 A.4, p. 24. 



Locality : Gulf of Manaar, three specimens (2 adult c? and 1 young ? ). 



Description: CI. of an adult male (front included) = 12 '00. The present 

 examples have only five teeth on the antero-lateral margin of the carapace (outer 

 orbital angle included) instead of six. It is the second tooth which is absent. 



Neptunus (Neptunus) sanguinolentus (Herbst, 1783) A.4, p. 32. 



Localities : Gulf of Manaar, one specimen ; Trincomalee, two specimens. 

 Description : Two females and a male all young. 



Neptunus (Neptunus) pelagicus (Linn.), 1764 A.4, p. 34. 



Locality : Off Chilaw, 2j to 4 miles off shore, one specimen (adult non-ovigerous ). 

 (Rathbun, ' Proc. Biol. Soc. Wash.,' xi., for genera of this and last species.) 

 Alcock unites N. pelagicus and N. trituberculatus. Miss Rathbun keeps them 

 apart (' Proc. U.S. Nat. Mus.,' vol. xxvi., p. 26, 1902). The present specimen comes 

 under N. pelagicus in Miss Rathbun's sense. Whitelegge's notes on variability 

 should be consulted (' Mem. Austral. Mus.,' iv., p. 154, 1900). He concludes, after 

 an examination of some hundreds of examples from Port Jackson, that the character 

 of the median tooth is not to be used as a specific distinction between the two species. 

 Perhaps the granulation of the carapace is much a matter of sex. This character is 

 in the present specimen of the type described by Whitelegge as essentially female. 

 Ortmann and Calman have cast doubt upon the specific distinctness of N. armatus 

 from the present species (C, p. 21). 



Neptunus (Amphitrite) gladiator (Fabricius, 1798) A.4, p. 35. 



Localities : Off Negombo, Gulf of Manaar, one specimen ; off Kaltura, two 

 specimens ; Galle, one specimen ; pearl banks, Gulf of Manaar, thirty specimens ; 

 coral reefs, Gulf of Manaar, four specimens ; Chilaw Paar, one specimen. 



Description : There are five ovigerous females, six adult but non-ovigerous females, 

 fifteen young females, one adult male, and twelve young males. 



The present specimens are small compared with some I have seen from Madras. I 

 give some measurements of three of the ovigerous females : 



C.b. is measured by a straight line uniting the notches between teeth 8 and 9. 



