102 



OKHAMANDAL MA I! INK /OOLOGY REPORT 



In 1he rase of Pinnoteres oxtrcum, recorded from the East Coast of America, the 

 female mill/ is commensal with Oxtn-it ri/yiitii-n, whilst the male is free-swimming. 



It is interesting to note from the preceding that only in the case of Pinnoteres 

 margaritifera is the carapace referred to as being much flattened. 



Specimens of Pinnoteres placunce, n. sp., arc jHtrlirtilttr/i/ characterised by being 

 so compressed dorso-veutrally as to be quite fiat. This, of course, is exactly what 

 one would expect to find in a species commensal with a bivalve in which the valves of 

 l he shell are so closely approximated as in the case of Placuna placenta. In this 

 connection it is interesting to note that P. placunw and P. globoms form two extremes 

 in the form assumed by the body. As we have seen, P. placuncB is remarkably 

 flattened, whereas P. globosus, as the specific name implies, is globular in appearance. 

 These facts serve to indicate the plasticity of the members of the genus and the 

 readiness with which they adapt themselves to their surroundings. 



It will be noticed that P. piaum is more or less cosmopolitan, having been 

 recorded from England and from New Zealand ; it would seem that other species of 

 I'irtnoteres are local variations- of P. pisum. The specific and restricted distribution 

 of certain of the species, such as P. margaritiferce and P. placunce, appears to confirm 

 this idea. 



The following is a list of the species of Pinnoteres recorded up to date, as far as we 

 have been able to ascertain, with their respective hosts and the localities where they 

 occur : 



SPECIES. 



P. pisum (Tennant) 



P. margaritiferce, Laurie 



]'. jilm-HiHi; llorncll and South- 

 well 



P. rouxi, M. Edwards 



1'. rillosus, Guir. 



/'. /Hirvulus, Stimpson 



]'. yMtofsun, Hcrab. Jaques 

 ( = obesus, Dana) 



P. relerum, Bosc. 



/'. abyesicola, Alcock and Hen- 

 derson 



/'. i-H/iifnifiin, Guerin Minivollc 



P. i'1/ii-itfi/xl, I >i- Man 



/'. i/fdeni 



P. iixtreum 



P. purpiireus, Alcock 

 P. mactricola, Alcock 



HOST. 



sp. 



Ceylon Pearl Oyster (M. vulyaris) 

 Placuna placenta. 



Pinna, sp. 



Meroe quadrata and Cythrea, sp. 



Lima indica 



Pearl Oyster 

 Osti-i'n, sp. 

 Pecten, sp. 



Ostrea riryinica (male free-swim- 

 ming, female only in oyster) 

 Ostrea, sj>. 

 Mactra violacea 



DISTRIBUTION. 



Mediterranean ; New Zealand 

 Ceylon Pearl Banks 

 Gulf of Kutch 



Indian Seas 

 I 



New Xealand 

 China Seas 



Off Travancore, 439 fms. 



Torres Straits 

 King Island Bay 

 E. coast of North America 

 Do. 



Andaman Islands 

 Hoogly River, India 



