82 THEBA CANTIANA. 
twenty-six in number, and somewhat unstable and irregular in general form and 
in the number and arrangement of the pectinations. 
The formula of a specimen from Walmer, Kent, collected by Mr. W. Whitwell 
in 1887, and photographed by Mr. W. Bagshaw, from a preparation by the late Mr. 
J. W. Neville, is 
26 41541415426 x 135 = 11,205 teeth. 
Reproduction and Development.—7heba cantiana has been noted 
in congress in most of the months from May to September, the seminal 
element being transferred by means of a spermatophore, which is closely 
Fic. 119. Fic. 120. Fic. 121. Fic. 122. 
Fic. 119.—Young shell of 7eba cantiana, showing its hispid character, Collingham, Mr. G. Fysher 
(from a magnified photograph by Mr. W. Bagshaw). 
Fic. 120.—Spermatheca of 7heba cantiana of normal aspect (greatly enlarged). 
Fic. 121.—Spermatheca as distorted by the contained rigid capreolus (greatly enlarged). 
Fic. 122.—Spermatophore removed from the spermatheca after conjugation (greatly enlarged). 
serrate along one side, and whose presence in the spermatheca of the 
partner snail is shown by the curious twisted appearance it assumes, 
caused by the rigid, corkscrew-shaped spermatophore, but no further 
details have been placed on record, though it is probable that the 
Fic. 123. Fic. 124. Fic. 125. Fic. 126. 
The Appendix, degenerate Dart-sac or ccecal excitatory organ of Theba cantiana, 
showing its quiescent form, and some of the changes occurring during sexual 
activity, greatly enlarged (slightly modified after Prof. Boycott). 
Fic. 123.—Ccecal diverticulum, or appendix, in its normal aspect when quiescent; with enlarged 
transverse sections, showing the lumen. 
Fic. 124.—Ccecum during or after conjugation and during the process of its withdrawal after 
eversion; and Fic. 125, a hypothetical longitudinal section thereof. 
Fic. 126.—The contracted coecum, also showing hypothetically the method of withdrawal in the 
earlier stages of its reinvagination ; with F, a transverse section through the central area, in which 
the dark portions represent the muscular walls of the organ; the inner and outermost spaces indicate 
its lumen, while the narrow intermediate space is connected and continuous with the body cavity. 
elongate vestige of the dart-sac is everted and used as an excitatory 
organ prior to pairing taking place, an act which may occur even before 
full growth is attained, the incomplete aperture of the shell being frequently 
