406 PROCEEDINGS OP THE ACADEMY OF [Sept., 



species of the same fj;eiius? Here again it is interesting to note that 

 Pleurotomnria and Haliotis rufescens agree, although Woodward, who 

 had very Uttle material, was not entirely sure of his ground. 



The basi-branchial sinus (PI. XXX, fig. 6, Si) is in reality but the 

 branchial end of the median pedal sinus, that receives also a few veins 

 {NV) from the right kidney. It is provided with a membranous valve 

 (F), which, like the aortic valve, has not been hitherto described, so far as 

 I am able to learn. The former suggests a like structure found in the 

 Cephalopoda that likewise prevents a backward flow of blood from the 

 ctenidia. Reaching these last-named organs through the afferent sinuses 

 (A/, Aj') the blood is collected by the efferent vessels (figs. C, D, Ef), 

 and with that of the pallial sinuses passes to the auricles, together with 

 blood brought by several minor veins. Here, as in H. iuberculata and 

 some other prosobranchs, there is a well-developed sinus connecting the 

 two auricles. 



Though difficult to demonstrate, it appears that the main venous 

 sinus, mentioned in the preceding paragraph, also partially drains 

 the visceral cavity and portions of the intestines. The kidney, espe- 

 ciall}^ the anterior portion, probably aids to a considerable extent in 

 the operation. But the larger part of the blood passing through this 

 organ is that distributed to the viscera, etc., by the visceral and genital 

 arteries. This is carried to the right kidney by a prominent sinus that 

 is seen lying at the border of the liver immediately behind the columel- 

 lar muscle, and above the genital artery. The blood is distributed 

 through the tissue of the kidney by means of a meshwork of fine vessels. 

 In conclusion it may be said that the blood from the papillar}' sac 

 drains into the basi-branchial sinus. 



Bibliography. 



BouviER, E. L. l^tude sur I'Organization des Ampullaires. Mem. publ. par la 



Societe Philomathique. 

 Erlanger, R. 1S92. On the Paired Nephridia oi' Prosobranchs. Quart. Jour. 



Mic. Sci., Vol. 33. 

 Fleure,H. J. 1902. Notes on the Relations of the Kidnej^in Haliotis fuhcrcu- 



lata. Ibid., Vol. 46. 

 Haller, B. 1885. Beitrage zur Kenntnis der Xiere die Prosobranchier. 



Mar ph. Jahrb., Bd. 11. 

 . 1894. Studien iiber Docoglosse und Rhipidoglosse Prosobrancliier, etc. 



Leipzig. 

 Lankester, E. R. 1881. On the Originally Bilateral Character of the Renal 



Organs of Prosobranchs, etc. Ann. Mag. Nat. Hist., (5), Vol. 7. 

 Pelseneer, p. 1898. Recherches morpholog. et phylog. sur les Molhisques 



archaic. Mem. I'Acad. ray. des sci. de Belgique, T. 57. 

 Thiele, J. 1897. Beitrage zur Kenntnis der Mollusken. Zcit. f. w. ZooL, 



Bd. (32. 



