1873.] F. Stoliczka — Land-shells of Penang Island. 21 



Judging from the similarity of the shells of these two groups and from 

 what we know of the animal of T. Ternatana, ohserved hy Martens, I very 

 much doubt that any necessity exists for subdividing the genus Trochomoiyha. 



Trochomoepha castra, {Benson). PL i, figs. 14-16 and pi. ii, figs. 7-9. 

 Helix castra, Benson, Ann. and Mag. Nat. Hist., 1852, vol. x, p. 349. — Reeve, 

 Conch. Icon., Helix, No. 1160. 



The shell is subject to a very considerable amount of variation as regards 

 the elevation of the spire. Young specimens are sometimes almost planor- 

 bular, and in some adults the total height of the shell is scarcely more than 

 one-third of the larger diameter, while in others it somewhat exceeds one 

 half of the same dimension. The width of the umbilicus varies from 

 0*2 to 0*3 of the diameter of the shell. The base is always distinctly 

 spirally striated, but on the upper side the oblique transverse striae of growth 

 prevail. The usual colour is pale horny, sometimes brown with a pale band 

 below the suture. 



The species is very rare on Penang hill, but it is common in Pegu, 

 Arakan, Assam, Sikkim, and within the last few years it became abundant 

 in the botanic garden near Calcutta, having been most likely introduced 

 from Darjeeling. One of the largest Sikkim specimens in my collection 

 measures : larger diam. 13, smaller diam. 12, height of shell 7, same of 

 apert. 3, width of same 5 '4 m.m. 



The animal changes from dark leaden to blackish grey, being always 

 paler at the sides of the foot, generally tinged with brownish below the pedal 

 row ; tentacles and pedicles mostly somewhat darker than the body ; neck dis- 

 tinctly warty ; sole dark grey, entire, without any distinct furrows ; tail gland 

 represented by a fine slit about one mill. long. The total length of the 

 foot generally equals one and a half diameters of the shell, the caudal portion 

 being always shorter than the anterior one. The mantle is blackish and in 

 its extent above the large pulmonary cavity variegated w^ith pale spots. 



The jaw is smooth, very thin, almost semicircular, with broad oblique 

 ends and a small, in younger specimens sometimes almost obsolete, projection 

 in the centre of the concave edge ; its width is about one half millimetre. 



The radula is narrow, about two mill, long, or slightly longer, composed 

 of about 85 transverse straight rows, there being about 101 teeth in each 

 of them. All have very sharp, long and pointed cusps, the central with a 

 small denticle on either side near the tip ; on the outer ones, as they turn 

 laterally and gradually decrease in size, the inner denticle disappears, while 

 the outer increases, until on the last 15 or 20 teeth, preceding the 3 or 

 4 terminal ones, it equals the principal cusp. The last few teeth are short, 

 broad, and their outer cusp becomes almost entirely obsolete, the teeth pre- 

 senting merely an oblique sharp edge. 



The female portion of the genital organs has a globular swelling near 

 its origin at the hermaphrodite opening, and the receptaculum seminis 



