32 



WALTER K. FISHER, 



having been exposed beneath the epithelium to air (at low tide) or 

 sea-water. During this exposure it is presumably aerated. 



The blood in the circumpallial artery reaches the heart from two 

 directions, very probably, the current dividing and setting forward 

 from somewhere in the posterior region of the body. From figures it 

 will be noted that the vessel is situated about midway between the 

 two edges of the mantle, if any thing closer to the free margin, and 





A^ 



nta-y t 



oV^tklànc 



cten'i<i'\UTTi 1^ 



^^ 



-?aU\ S> 



^^'Ve.h^\ S"inu.ses 



nvricle 

 Diagram of circulation of Lottia gigantea, 



*" not, as Haller figures it, near the inner or attached edge. I strongly 

 suspect this investigator has confused the circumpallial vessel ("Mantel- 

 randvene") with the vein shown clearly in Fig. 19 near the inner 

 edge of the mantle. This, of course, is in the venous circulation of 

 the mantle. (Diagram.) 



Ctenidium. The single ctenidium is located in the leftside of 

 the mantle cavity and extends obliquely forward and slightly toward the 

 right. It is attached by its base to the wall of the mantle cavity 



