THE ANNALS AND MAGAZINE OF NATURAL HISTORY. [FOURTH SERIES.] No. 15. MARCH 1869. XXIV. — On the Animal and Operculumof Georissa, W. Blanf.. and on its relations to Hydrocena, Parreyss ; with a Note on Hydrocena tersa, Bens., and H. milium, Bens. By William T. Blanford, A.R.S.M., C.M.Z.S., &c. [Plate XVI.] In the 'Annals and Magazine of Natural History' for June 1864, ser. 3. vol. xiii. p. 463, I pointed out that some small land-shells from the Khasi Hills and Burma, described by Mr. Benson as species of Hydrocena, differed so much in the characters of the animal and operculum from the other forms classed in that genus by Pfeiffer and other conchologists, that it was necessary to found a new genus for their reception ; and I suggested that this genus, which I proposed to call Georissa, might be an ally of Helicina, which it resembled in the absence of spiral structure in the operculum. Recently Capt. Godwin-Austen has had opportunities of examining living specimens of Georissa sarrita, Bens., in the Khasi Hills, and he has very kindly placed his drawings at my disposal, calling attention to one point which I had overlooked : this is the existence of a projection on the inner side of the operculum, somewhat re-sembling that in Rissoina. This projection is so brittle that, unless great care be used in extracting the operculum, it is sure to be broken, as it was in the two or three specimens which I examined in 1864. On hearing of this, I reexamined the opercula of the three species of Georissa of which I possessed specimens, viz. G. pyxis , Bs., G.frustillum, Bs., and G. sarrita, Bs., and found the projection in all, varying slightly in form. Both Capt. Godwin-Austen and I have also examined the lingual teeth, and found that, although they belong to the Rhipidoglossate type, they differ entirely from those of Heli-cina and its allies. Capt. Godwin-Austen could detect no teeth Ann, & Mag. N. Hist. Ser. 4, Vol.m. 13
XXIV.—On the animal and operculum of Georissa, W. Blanf., and on its relations to Hydrocena, Parreyss; with a note on Hydrocena tersa, Bens., and H. milium, Bens
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