1908. BowELL. — O71 the Aiiatomy of Vitriiia pyrenaica. 95 



{g'O., figs. D and K) is large; the *'balancier" {b.) covers the 

 spire of the shell. 



Figure E represents a dissection, in which the integument 

 has been divided longitudinally, and reflected {f.i.) ; p.g. shows 

 the position of the scale-like grooves along the edge of the 

 foot. The radular sac, r.s.^ has been gentl}^ drawn aside and 

 turned half over, so as to display the collar of ganglia in 

 profile ; a: is the oesophagus, and s.g. the salivary glands 

 (about half of their length). The flagelluni, which normally 

 covers the spermatheca and its duct, has been drawn over to 

 the outside; figure F shows the same organ {fl) in its normal 

 position. The vagina appears at v. ; the lower part of the 

 line dividingJt from the spermathecal duct {sth, d.) is really 

 only part of a fold in the fine membranous bag which sur 

 -rounds all these organs. This bag, of which it is impossible 

 to form a just idea without actually dissecting a fixed 

 specimen in a medium of high refractive index, encloses 

 the whole of the flagelluni and spermatheca, each of 

 them having a separate pocket. It is doubly folded round 

 the male organ (/>.), which can be completely everted, and it 

 afterwards joins the walls of the atrium. A part of it is the 

 retractor muscle {r.7?i.), which has led some authors to describe 

 the {d.v.d.) inferior dilatation of the vas deferens as the intro- 

 mittent organ and sac. This dilatation looks also ver}' much 

 like a dart-sac; but the first objection to that is that the 

 apparent dart is turned the wrong wa5^ It is quite probable 

 that it may be the place where the capreolus is secreted, but 

 I have not found an example, The true course of the vas 

 deferens is shown in figure H, which should be compared 

 with figure K. in which the proximal parts of these organs in 

 V. pelhtcida are shown. The penis sheath {p-s^ is similar in 

 shape to the organ discovered b}' Messrs. Moss and Paulden in 

 Helicella barbara, but in this Vitrina it is merely a soft bag of 

 connective tissue, without any signs of chitinisation or cal- 

 careous deposit. The dilatation {d.v.d.) is merel}^ in the form 

 of a sigmoid flexure, with the sides appressed, and the whole 

 covered over with a fold of the enclosing bag ; its similarity 

 to a penis or dart-sac is purely superficial. The retractor 

 muscle is not uncommon in this position.^ The same dilata- 



^ Proc. Malac. Soc^ vol. viii., p. 53. 



