ANATOMY OF SCAPHULA. 



lUi 



to bring the anus directly in the line of the outward current of 

 water and the exhaiant aperture, aiid this is perhaps correlated 

 with the depth of the posterior region below and behind the 

 posterior adductor. Iii Acar the great depth of the mantle is 

 attended by a great elongation of the projecting tube of the 



Text-fi<iure 5. 



A gill-filament of S. celox (outer and inner deraibrancli). 



rectum. In conclusion it might be noted that the present genus 

 might have originated amongst and be related to Byssarca and 

 Barhatia, although modified and perhaps degenerate owing to its 

 fiuviatile life. 



SCAPHULA MINUTA, Sp. n. 



Specimens of this species were collected by Dr. N. Annandale, 

 who kindly gave me the following information : — The species 

 occurs all over the Tale Sap or Inland Sea of Singgora on the 



Text- figure 6. 



Shell of S. minuta, outer surface (left valve). 



east coast of peninsular Siam. It was found attached to weeds 

 and stones in both fresh and brackish water. The specimens I 

 have examined were found adhering to water-plants by several 

 byssus threads. 



76* 



