7Q 



MOLLUSCA OF INDIA. 



Hemiplecta? tranqueharica, W. T. Blanford, A. M. N. Hist. Feb. 



-I Q/:»o 



Hemiplecta, sec. A, Theob. Cat. L. & Freshw Moll. Ind p. 22^ 

 Nayiina {Xesta 2 Acusta T) tranquebarica, ^evill, Hand-list, i»/», 



D. 51. 



" Hemiplecta, in nomencL, Pfr. Mon. Helic. 1848. .., 



Xesta tranquebarica, ^emi^er, neis. Philippinen, Land Moll. m. 



1870, p. 65, pi. iii. %. 20, pi. V. figs. 13-23, pi. vu fig. 10. 



Description (in Pfeiffer) :— " T. amjuste umbiUcata, globosa, 



crassa, distincte striata, lineis obsoletis saperne decussafu, aibida ; 



spira ehvata ; anf. 5^, conveximculi, idtimus antice descendens ; 



apertum lineato-ovalis, intus lactea ; perist. suhncrassatum ; 



marginihus convergentlbus, columeUari calloso, rejlexo, umbiLicum 



noil teqente. .„ .,r n ■ \ 



"Diam. maj. 24, min. 17-, alt. 15 mill. (Mus. Cuming). 

 " Habitat in Tranquebar.'' . , i. j 



Animal. No sbell-lobes (PI. LXXXI.fig. 3) ; a tnangular-shaped 



rigbt dorsal lobe and a long narrow left dorsal lobe ; toot not 



^'^Generative orqans (figs. 3«&36). The retractor muscle of the male 

 organ is given off from an extremely long diverticulum, the c,e,cum 

 mlscuU refractoris penis" of Semper. Where the vas deferens 

 ioins the sheath there is a well- developed kalk-sac ; this, with a 

 portion which follows, is nearly equal in length to the diverticulum 

 above mentioned. From where this is given off the sheath is a 

 long and narrow tube, found rolled together (as in fig. 6 b); 

 when separated out it is irregular in diameter and stiU con- 

 volute The spermatheca is bulbous ou a short narrow neck. 

 The amatorial organ is very massive and thickened towards the 

 posterior end ; in the centre is a long, hard, cyhndrical rod, ronnded 

 at the posterior ead, with a rather blunt point at the anterior. 

 Below the ovo-testis there is a sort of kink in the vaginal tube. 



In one specimen dissected I was fortunate to secure in most 

 perfect preservation three spermatophores, ot one of which I give a 

 drawing (figs. 3 c, 3 d). It consists of a long narrow bag (9 mm. m 

 length), tapering to a fine tube. This bag is attached to a hard 

 chitinous, curved sort of gutter, set on one side with the usual 

 spines These, however, are characteristic, being arranged m 

 bunches at regular intervals, and are not unlike the head of a many- 

 tined fish-spear; they consist of four equal sharp spikes rising 

 from a single short stalk, flower-like in form, and about 10 were 

 counted. In this character it differs from the spermatophore ot 

 other genera with which I am acquainted. 



Jaw (PI. LXXXII. fig. 3) arched above, with a central projection. 

 The radula (figs. 3a-3 c) agrees on the whole with that of iV^. solata, 

 but the median teeth are tricuspid, the inner cusp higher than the 

 outer, while the outermost teeth are longer and not evenly bicuspid. 

 Nos. 17, 18, and 19 differ in no respect. The formula is— 

 54 . 3 . 17 . 1 . 17 . 3 . 54 

 74 . 1 . 74 



PAKT VIII. 



