Lagochilus.] GASTROPODA. 177 



traverse the nerve-collar. The oesophagus is nearly always devoid of 

 an unpaired gland. Usually there is neither a proboscis nor a siphon. 



The suborder includes two distinct groups or tribes, which are 

 respectively creeping and swimming forms- namely, the Platypoda 

 and Heteropoda. 



Tribe 1. PLATYPODA. 



Normal Tcenioglossa, but slightly modified, and of creeping habit. 

 The foot is flattened ventrally at all events, in its anterior part. 

 The otocysts are situated close to the pedal nerve-centres. Accessory 

 organs are rarely found on the genital ducts, but are present in Vivi- 

 para. Cyclostoma, the Naticidce, Catyptrceidce, &c. Mandibles are 

 usually present. The intestine is long. 



The Platijpoda form the largest group of the Mollusca, comprising 

 nearly sixty families of unequal value, some of which are not thoroughly 

 well known from an anatomical point of view. 



Fam. CYCLOPHORIDJE, Gray. 



Animal having long cylindrical tentacles, subulate toward the 

 extremities ; eyes at their outer bases on very short peduncles ; foot 

 long, attenuate behind. Pallial cavity devoid of a ctenidium and 

 transformed into a lung ; pedal centres in the form of ganglionated 

 cords ; otocysts with otoconia. Jaws reticulate. Radula having the 

 formula 2.1.1.1.2; central tooth contracted in the tniddle, with 

 3 to 5 cusps ; lateral and marginal teeth arranged in oblique rows 

 curved, all of the same form, and with 2 or 3 cusps. 



Shell conical or depressed, usually covered with a horny epidermis ; 

 aperture circular, peristome simple or reflexed ; operculum distinctly 

 spiral, testaceous or horny ; whorls very numerous and subequal, or 

 few and rapidly increasing. 



These molluscs are terrestrial, and appear first in the Cretaceous. 



Genus 1. LAGOCHILUS, Blanford, 1864. 



Lagochilus. Blauford, A.M.N.H. (3), xiii, 452. Type : L. tomotrema, Benson. 

 Lagochilus, Blanford : Moellendorff. P.L.S. N.S.W. (2), vii, 1892. 385 ; 

 P. and F. Sarasin, " Die Land-Mollusken von Celebes," 1899, 25. 



Animal having a glandular slit at the extremity of the foot. 



The teeth of radula are distinguished from those of Leptopoma 

 by the sharply pointed cusps of nearly equal size, none of them being 

 much broader than the others. 



Shell conoidal, subturbinate, thin, with an epidermis. Aperture 

 circular ; peristome mostly reflected, forming a more or less distinct 

 angle or slit at its insertion above. Operculum circular, thin, horny, 

 with 7 to 9 volutions, the margins of which are sometimes slightly 

 elevated upon the outer face. 



Distribution. The genus ranges from India and China to the 

 Philippines, the Malayan Archipelago, New Guinea, and New Zealand. 



