340 Records of the Indian Museum. [Vol. IX, 1913.] 



The 2nd antennae also show the nipple-like termination of the 

 exopodite as in all adult males of both Paracalanus and Acrocalanus. 



As regards the swimming legs, these closely resemble those of 

 Paracalanus parvus : in the 2nd-4th pairs of legs, both exopod 2 

 and 3 have serrated margins, and the distal as well as the proximal 

 part of the border of the 3rd exopod bears teeth. 



The 5th pair of legs is asymmetrical, but the most striking 

 feature in this species is the remarkable length of the right leg ; 

 this consists of the usual number of segments, but when folded 

 back it reaches beyond the tip of the furca by the last two seg- 

 ments, whereas in the other males of the genera, it only reaches 

 to the last abdominal segment. 



T. Scott has described a form P. pygmaeus from the Gulf of 

 Guinea ; according to Giesbrecht this is the same as P. crassiros- 

 tris, Dahl; but his description of the female, which was the only 

 sex he obtained, while closely resembling the present specimens as 

 regards the general shape of the body, yet differs very materially 

 in the arrangement of the spines on the swimming feet: according 

 to him, his examples possessed spines on both the last joints of 

 the 2nd-4th swimming feet : in the present specimens, spinulation 

 was completely absent in exopod 2 in all the swimming feet of the 

 5 , nor in this sex was there any trace of spines on the distal part 

 of the margin in exopod 3. I am inclined, therefore, to believe, 

 that these two forms are not the same. 



Thompson and Scott have recorded P, crassirostris from the 

 coastal waters of Ceylon, I have recently examined a large collec- 

 tion from the Ceylon Pearl Banks, but have seen no examples of 

 this species. 



It is interesting to note that Dahl's specimens were obtained 

 in brackish water having a salinity ranging from ii'8 to I2"8. 



2. Acartia ceniriira, Giesbrecht. 



This species seems to be a common inhabitant of Indian 

 waters. The examples in the present collection are interesting in 

 that they are slightly smaller than the normal, measuring cf i'028 : 

 9 1-13. 



In both sexes the general structure of the body and appendages 

 is as in normal examples, but the spines on the posterior thoracic 

 margin, and the distal border of the abdominal segments are much 

 smaller than is the case in specimens obtained in the open sea. 

 It would seem probable that these are a " depauperized " form. 



3. Oithona sp. 

 Not only were numerous adults of all species present, but also 

 a large numV>er of immature forms and nauplii larvae, thus show- 

 ing that the three species were all actively breeding in the lake. 



R. B. Seymour Sewkli.. 



END OF VOL. IX. 



