COMPARATIVE ANATOMY 



CHAT. 



Okder 2. Pulmonata. 



The pleuro-visoeral connectives are not crossed. The ctenidium has disappeared 

 from the mantle complex and is replaced by a lung, or respiratory vascular network, 

 on the inner surface of the mantle. The pallial organs lie primitively to the right, 

 anteriorly on the visceral dome. The edge of the mantle, with the exception of a 

 branchial aperture on the right, imites with the integument of the neck. In terres- 

 trial Pulmonata the visceral dome is often 

 flattened down and the shell becomes rudi- 

 mentary (Slugs). The operculum is always 

 wanting. The heart has one auricle, which 

 almost always lies anteriorly to the ventricle. 

 The Pulmonata are hermaphrodites with herma- 

 phrodite glands or ovotestes, and complicated 

 efferent ducts. They are either terrestrial or 

 fresh -water. 



Fio. 10. — Amphipeplea leuoonensis 

 (after Adams). », Lobe of the mantle 

 bent back over the .shell ; &, portion of 

 the shell uncovered ; c, foot. 



Sub-Order 1. Basommatophora (fresh-water). 



Eyes at the bases of the non-invaginable 

 optic tentacles. Genital apertures separate, to 

 the right anteriorly, the male in front of the female. Fam. Livmmidcc, (Limnaia, 

 Amphipeplea [Fig. 10], Physa [Fig. 11], Planorhis, Aneyhis), Auricvlida: 



Fig. 11.— Physa fontinalis (after L. Reeve), w, Mantle lobes folded back over the shell ; 6, 

 evaginated penis. 



Eyes at the tips of the oj)tic tentacles ; tentacles iuvaginable. 



Sub-Order 2. Stylommatophora. 



a. Monogonopora. — With a single genital aperture to the right. Fam. HelicidEe 

 (Helix [Fig. 12, A], Arion [Fig. 12, D], Bulimus). Testacellidse {DavxUhardia 

 [Fig. 12, B\ Tcstacella [Fig. 12, G]. LimacidSB [Ariophaiita, Umax, Vitrina, 

 Zonites, Heliearion). Bulimulidae (Fig. 13), Pupidse (Bxilimimis, Pupa, C'lausifia), 

 Succiueidse. 



b. Digonopora.— Shell-less snails with separate male and female genital apertures, 

 the male anterior, the female at the posterior end of the body, both to the rio-bt. 

 Pallial complex at the posterior end of the body, lung cavity reduced. Fam. Vagi- 

 nulidse (terrestrial), Onoidiidse (marine or amphibious) ; respiration partly by means 

 of dorsal branchial appendages. 



