1872.] F. Stoliczka — On the Cychstomacea of JPenangl 260 



having the constricted portion of the last whorl much more produced and 

 very much deflected, the height of the shell being also considerably less than 

 the larger diameter of the shell. Eydoux who collected the species at 

 Touranne in Cochin-China, says in his original description,* that the 

 operculum is membranaceous and not multispiral. 



The species is not uncommon along the base of the hills in thick jun- 

 gle, under and on large blocks of rocks, generally between half decomposed 

 vegetable matter. 



The animal is dusky grey, foot pale; tentacles long, pale at the base, 

 further on dark, especially at the tips which are slightly thickened ; eyes 

 small, placed laterally at the bases of the tentacles, but the bulgings are 

 not distinct ; rostrum long, cleft at the end, reddish at the base on account 

 of the fleshy coloiu- of the manducatory apparatus. 



Fam. — Laqocheilims. 



Genus. Lagocheilus, Theobald. 

 Conip. Blanford in Ann. and Mag. N. EL, third Ser., 1864, vol. XIII, p. 452. 



Shell conoid sub-turbinate and perforated, thin, covered with a horny 

 cuticle ; aperture round toith a narrow incision in the upper or posterior 

 angle; operculum thin, homy , multispiral. Animal of the usual Gyclopho- 

 rid type, but toith a glandular slit at the upper posterior end of the foot. 



The shell of Lagocheilus, when the cuticle is removed, merely differs 

 from Leptopoma by the slight incision in the posterior angle of the aper- 

 ture. When Mr. Theobald suggested the above name, it could scarcely 

 have been anticipated that such a. comparatively insignificant character will 

 be accompanied by a most important structural distinction in the anatomy of 

 the animal. Mr. Blanford, already many years past, noticed that the animal 

 of the Barmese Lagocheilus leporinus^ has the peculiarity of possessing a 

 groove down the middle of the upper caudal portion of the foot. Since then 

 I had observed the animals of L. tomotrema, of two new species .from Penang, 

 and of two other species from the Nicobars, and I find that all the 

 animals posses a long glandular slit at the upper end of the foot, and 

 that the incision in the apertural margin is the result of the presence of 

 this pedal slit. This instance is an excellent illustration of the occasional 

 intimate structure and the relation of the animal to its shell. 



Lagocheilus, together with Dermatocera, has evidently among the Ctclo- 

 stomacea the same systematic position, as the Zonitidje have among the 

 Helicacea. The external character of the animal of Lagocheilus is accom- 

 panied by some peculiarities in the dentition and in the internal organs with 

 which I hope to deal at some future occasion, in connection with a general 

 account of the anatomy of the Indian Cycxostomacea. 



* Guerin-Meneville's Magasin de Zoologie, for 1S3S. 

 f Journal A. S. B. for 1865, PL II. p. 82. 



