THE GASTROPODA 



107 



genus the appendage is to the left of the pallial aperture). In 

 Planwbis wrneus (Fig. 89, g) there is a single respiratory lobe, with 

 a richly vascularised surface, and in Ancylus there is a similar 



FIG. 88. 



Diagram of a sagittal section of Patella vulgata. br.a, branchial afferent vessel (artery) ; 

 br.v, branchial efferent vessel (vein) ; b.r, blood-vessel ; c, muscular substance forming the root 

 of the foot ; cor, heart within the ]>ericardium ; e, mantle-skirt ; /, papilla of the larger kidney ; 

 g, anus ; i, smaller kidney ; k, larger kidney ; I, pericardium ; n, liver ; o, mouth ; od.m, muscles 

 and cartilage of the odontophore ; j>, snout ; q, intestine in transverse section ; r, radular or 

 lingual sac ; rd, radula ; s, lamellated stomach ; t, salivary gland ; v, duct of same ; r, buccal 

 cavity ; w, gonad. (After Lankester.) 



structure, but the lung has disappeared. In Bulinus, including 

 the sub-genera Isidom, Pulmobranchia, etc., and in Miratesta there 

 is a folded branchia. In Siphonaria the long plicated branchia 

 which extends across the interior of the roof of the pulmonary 



Planorbis corneus, removed from the shell ; anterior view, o, anus ; /, foot ; g, #11 ; fc.o, 

 renal aperture ; m, mouth ; as, osphradium ; pa, mantle ; pn, pneumostome ; si, pulmonary 

 siphon. 



cavity, between the kidney and the rectum, is of the same 

 character. This branchia is situated more posteriorly and to the 

 right than the ctenidium of monobranchiate Gastropods (Fig. 174). 

 The diverse characters of the respiratory apparatus of Gastropoda 

 may be advantageously summed up in the following table : 



