26 F. Stoliczka — Land-shalh of Vennng Island. [No. 1, 



othor end, where the penis begins, is a retractor muscle. The penis itself has 

 near its base a ccccal appendage ; its terminal portion, before it joins the 

 hermapln-odite opening, is very thin. 



A comparison of the genital organs with those of Trachia delihrata, 

 represented in J. A. S. B., vol. XL, Pt. II, 1871, pi. xvi, fig. 1, will shew, 

 that the only essential difference consists in the presence of the small 

 coecal appendage on the penis in T. Penangensis. The jaw has fewer and 

 less strong ribs, than that of the former species, but the teeth themselves 

 are extremely similar. 



Taking all these anatomical characters together with those of the shell, 

 as noticed in my paper cited above, I think we can consider Trachia as a 

 fairly established genus of the Helicid^. 



Helix [Fruticicola] similaris, Fer. PI. ii, figs. 1-3. 

 Comp. E. v. Martens'Jn Preuss. Exped. nach Ost-Asien, vol. II, pp. 43 and 270, 

 etc. Stoliczka in J. A. S. B. vol. XL, Pt. II, 1871, p. 224. 



On Penang this species is mostly found in the coco-palm plantations 

 up to a height of about 200 feet, never in the interior of large forests and 

 at great elevations. The shells are of the usual small size (larger diara. 

 between 12 and 13 m.m.), with or without a brown peripherical band. The 

 strise of growth are generally fine, but in some specimens they accumulate 

 to strong ribs which give the shell a very peculiar costate appearance. 



I also obtained the species from Malacca, near Singapore, Hongkong, 

 Chusan, Maccao, Canton, &c., northwards it extends through Tenaserim into 

 Burma, where it is associated with a great number of closely allied species, 

 some of which may prove to be mere varieties of it. I may mention 

 JI. bolus, H. scalpturrita, H. Zoroaster, &c. 



In Bengal itself the species is not known, but in Central India it is 

 represented by S. propinq^ua, and on the Andamans by S. liemioyta. 

 Judging from the great number of closely allied species in the Indo-Malay- 

 an region, there is certainly the greatest probability that the original habitat 

 of H. similaris falls within the Indo-Malayan Archipelago, and that it has 

 been introduced into Mauritius, China and South America. 



The animal is rather slender, all over strongly wai'ty, brownish fleshy 

 white, or pale brown, the jpedal row is very slightly indicated by a fine 

 groove ; the pedicles and tentacles are greyish white, mantle dull milky white 

 with a slight vermilion tinge. When the animal is quite fresh the total 

 length of the foot is equal to from two and a half to three longer diameters 

 of ^he shell. 



The jaw is semilunar, about 1 m.m. broad, with three strong central 

 ribs, followed by a somewhat broader one on either side, while the next is 

 only indicated by a faint dark line. 



