[CEYLON PEARL OYSTER FISHERIES -1906 SUPPLEMENTARY REPORTS, No XXXVII.] 



EEPORT 



ON 



JOUSSEAUMIA 



A NEW GENUS OF EULAMELLIBRANCHS COMMENSAL WITH THE CORALS 

 HETEROCYATHUS AND HETEROPSAMMIA 



COLLECTED BY 



Professor HERDMAN, at CEYLON, in 1902. 



BY 



GILBERT C. BOURNE, MA., D.Sc, F.L.S., 



FELLOW OF MERTON COLLEGE, OXFORD, LINACRE PROFE8SOR OF 

 COMPARATIVE ANATOMY. 



[With THREE PLATES.] 



In a very interesting paper describing the true nature of the commensalism between 

 corals of the genera Heteropsammia and Heterocyathus and a Sipunculid belonging 

 to the genus Aspidosiphon, E. L. Botjvier (4) pointed out that there is a third 

 partner in the commensalism in the form of a minute Lamellibranch which he figured 

 and named Kellia deshayesi, without, however, giving any diagnosis of the species. 

 As I shall point out in the course of this report, Botjvier's figure, though it gives a 

 correct enough representation of the external form of the Mollusc, as seen lying in 

 the left valve of its shell, is incorrect in the representation of the hinge teeth, and the 

 Lamellibranch in question certainly does not belong to the genus Kellia, differing 

 from it not only in the hinge teeth, but also in the sutural unions of the mantle edges 

 and in other important particulars. Though BouviER announced that his colleague 

 M. Jousseaume intended to make a study of this commensal Lamellibranch, it does 

 not appear to have been described or to have attracted any further notice until 

 Dr. A. E. Shipley in his report on the Gephyrea collected by Professor Herdman 

 in Ceylon (13) mentioned its occurrence along with Aspidosiphon in the basal 



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