TROCHO:MOEPnA. «"> 



the teeth arranged +9:11:1:11:9+? It was unfortunately 

 imperfect on both the lateral sides, where tlie teeth are very 

 small. The twenty-two centrals ai'e plain straight-sided teeth, 

 the centre tooth not so broad as those on either side ; the laterals 

 are curved, short, and evenly bicuspid. 



"The generative organs. — The vas deferens joins the male organ 

 below the retractor muscle attachment, and at its junction is 

 closely coiled upon itself ; this was seen in two specimens dis- 

 sected. The spermatheca is only of moderate length, and thus 

 these organs have a very distinct construction to that which 

 Stoliczka describes .in Sivella castra. The other parts of the 

 generative organs do not call for any special mention.'' 



Subgenus SIVELLA, Blanford. 



Sivella, Blanford, A. M. N. H. ser. 3, xi, 18G3, p. 86 ; Pilsbry, Man. 

 Conch, ser. '2, ix, 1893, p. 3. 



Type, Helix castra, Benson. 



Range. India and China. 



Shell depressed, acutely keeled, thin ; umbilicus wide. Sper- 

 matheca with a long duct. 



The only species of this group which appears to have been 

 examined anatomically is the type. Godwin-Austen states (Proc. 

 Zool. Soc. 1895, p. 450): — "It differs in every respect from 

 Discus \yidena\ represented by hicolor, sidcipes, &c." As he 

 refers all the forms from the Andaman and Nicobar Islands to 

 Discus, and as conchologically the two subgenera are indistin- 

 guishable, the only logical conclusion appears to be that the con- 

 tinental species should be classed under Sivella and the insular 

 ones placed in Videna, until an examination of the soft parts shall 

 prove the contrary'. 



1. Trochoniorpha castra, Benson. 



JMLv castra, Benson, A.M. X. II. ser. 2, x, 1852, p. 349; Keeve, 

 Conch. Icon, vii, 18o3, pi. 172, tig. 1100; Hanley & Theobald, 

 Conch. India, 1872, pi. 83, figs. 1-3. 



Trochomorpha castra, Stoliczka, J. A. S. B. 1873, p. 21, pi. i, figs. 14- 

 16 (shell), pi. ii, tigs. 7-9 (anat.) ; Nevill, Ilaud List, i, 1878, p. 56 ; 

 Marten.-^, Conch. Mitth. ii, 1883, p. 130; CoUinge, Jouru. Malac. 

 ix, 1902, p. 81. 



Sivella castra, Blanford, A.M.N. II. ser. :}, xi, 1863, p. 86; Godwin- 

 Austen, Proc. Mai. Soc. London, i, 1895, p. 284, pi. ix, fig. 5 

 (anatomv). 



Trochomorpha ( Videna) castra, Pfeiffer & Clessiu, Xomencl. llelic. 

 Viv. 1881, p. 84. 



Helix {Trochojyiorpha) castra, Tryou, Man. Conch, ser. 2, iii, 1887, 

 p. 84, pi. 16, figs. 5-7. 



Original description : — '* T. mediocriter umbilicata, depres- 

 sissimo-conica, tenuis, exiliter oblique acuto-striatida, cornea ; 

 spira ad apicem obtusa, sutura marginatis ; anfr. oh planulati, 



b2 



