124 LAND AND FRESHWATER 



the usual division of this lobe. As in W. iranqueharica and 

 JV. histrialis, the muscular diverticulum (crp, fig. 1 c) is very long, 

 near to its base (a portion of the penis which Semper calls the 

 " ccfcum musculi retracioris 2i^nis ") strong muscles attach it closely 

 to the penis-sheath, and a long free portion is coiled tightly together 

 and returns to the same point. A short free portion extends to the 

 junction of the vas deferens, and the part analogous to the flagellum 

 is verj' short. The spcrmathoca is oval, small, and sessile ; the 

 amatorial organ of moderate size. The salivary gland is spread out 

 widely and thinly over the surface of the alimentary canal, which is 

 expanded behind the oesophagus into a long ample sac. 



Among the many interesting molluscs sent me by Mr. 0. Collett 

 was li. chenui of Benson, which, as will be shown from the drawings 

 and description I have made of its anatomy, falls into this genus. 

 Purthermore it can be placed in the grouping of Ariophanta and 

 JVih/iria (vide p. 82), with the South-Indian N. bistrialis, the laterals 

 being aculeate and the median teeth bicuspid. 



NiLGiEiA CHENUI, Pfr. (Plate XCVI. figs. 1-9.) 



Helix chenui, Pfr. in Zeitschr. f. Malak. p. 145 (1847) ; Chemn. 

 ed. ii. Helix, no. 739, t. 119. figs. 14-16 ; Pfr. Mon. Hel. vol. i. 

 p. 438; Reeve, Conch. Icon. Ixxii. fig. 370; Hanley, Conch. Ind. 

 p. 13, pi. XXV. fig. 1. 



Helix cJienui, var., Hanley, Conch. Ind. p. 13, pi. xxvii. fig. 4. 



Hemiplecta (sec. D) chenui, Theob. Supp. Cat. p. 22. 



Nanina (Hemijylecta) chenui, Nevill, Hand-list., p. 47. 



Hemiplecta chenui, Clessin, Nomen. Helic. j). 50 ; Tryon, Man. 

 Conch, p. 38. 



Description in Mon. Hel. : — '•'•T.suhperforata, cJepressa, tenuiusculn, 

 striis subtilihus et lineis impressis spiralihus malleato-suhdecussata *, 

 castaneo-fvlva ; spira ohtusa ; anfr. 4^, pilanitisculi, ad nuttiram 

 rur/oso-striati, idtimus anrjidatus, non descendens, fascia p>eripherica 

 pallida et adjacente castanea, deorsum cliluta ornatus ; apertura 

 parum ohliqua, truncato-ovalis, intus opalina ; pei'ist. rectum, sub- 

 simplex, m,argine columellari subincrassato, ad perforationem clausam 

 breviter dilatato-rejiexo. 



" Diam. 40, alt!^ 20 mill. 



" Habitat dicitur in insula Ceylon. 



" Nahe verwandt mit Hd. bulla und sar/ittifera." 



The first of these is the type of Professor Semper's Group B of 

 the genus Rhysota, with very different genitalia and odontophore. 



Mr. 0. Collett writes in Journ. Roy. Asiat. Soc. Ceylon Branch, 

 no. 48, vol. XV. 1897, p. 2 : — " This species is fairly common 

 throughout the district ( Ambagamuwa, Ceylon). It closely resembles 

 the South-Indian form //. chenui, with which it is in all probability 



* The sutural edge is crinkled bj- the transverse folds of growth, and these 

 are cro.«sed byratlier obscure longitudinal lines where they are finer and stronger 

 (Plate XCVIII. fig. 3). 



