1873.] F. Stoliczka — Land-shells of Penang Island. 17 



Maceochlamts* stephoides, n. sp. PL i, fig. 9, and pi. ii, figs. 19-20. 



M. orbiculata, spira depresse convexiuscula, basi medio concaviuscula, 

 angustissiine perforata, tenui, succineo cornea, unieolore, circa umbilicum 

 albescente ; anfractibus sex, lentissime accrescentibus, sutura lineari junctis, 

 infra suturam angustissime adpressis, nitidis, fere politis, striis incrementi 

 transversis minutissimis, nonnunquam fere omnino obsoletis, notatis, supra 

 convexiusculis ; ultimo ad peripheriam fere uniforme convexo ; apertura sub- 

 semilunari, vix obliqua, labio per-tenui, labro simplici, ad basin paulum si- 

 nuose producto, ad insertionem umbilicalem anguste atque breviter refiexo. 

 Diam. maj. 11*6, d. min. 10*7, alt. 7 ; alt. apert. cum perist. 4'8, ejusdem lat. 

 5'6 m.m. 



The nearest ally of this species, as regards general character and size, is 

 the Andamanese 3Iacroch. stephus,f (Benson), differing from the present 

 species by a somewhat more depressed form and by having the sides of the 

 spire nearly straight or slightly concave, but not convex. Macrocli. liyali- 

 na,X Martens, is also very closely allied, it is a larger shell and with a more 

 rapid increase of the volutions, the difference between the smaller and larger 

 diameters being 2 5 m.m. In Burma and Sikkim several other allied forms 

 occur, such as 3f. hi/^oleuca, patane, jpetasus, &c., but they are all smaller 

 and more depressed shells. 



The species is rare ; I found a single live specimen and half a dozen 

 of old shells at the base of Penang hill, about 300 feet. 



The animal is long and very slender, blackish grey above and on the 

 pedicles, paler at the sides of the foot, which has a long and thin horn above 

 the tail gland. Both shell and neck lobes are well develoj^ed, the right ones 

 larger than the respective left ones. The two shell lobes are linguiform, 

 and the right one, w^hen fully expanded, covers almost half of the upper sur- 

 face of the shell. The lower portion of the left neck-lobe is merely repre- 

 sented by a slightly thickened rim, extending from the place of insertion of 

 the left shell-lobe to near the umbihcus. 



The jaw is one mill, broad, with a central rounded tooth in the concave 

 edge and with the corners somewhat bent outwardly ; a form which is also 

 met with in several other species of 3IacrocliIamys. 



The radula has not been seen perfect, but it does not appear to have 

 been more than four mill, long, and there appear to have been at least 101 

 teeth in each transverse row ; all with very sharp points ; the central with 



* Comp. Journ. A. S. B., vol. xl, pt. ii, 1871, p. 246. 



t The figure of this species in Conch. Inch, pi. 62, is taken from a joiing- or im- 

 perfect specimen, in which the peculiarly deijrcssed form is not so well discornablo as 

 in an adult shell. Fig. 6 on the same plate is incorrect, because it does not shew the 

 sinuoscly produced median basal portion of the peristome. 



X Prouss. Expcd. nach Ost Asiun, II, p. 241, pi. 12, fig. 5. 



3 



6 j -b i 1 



