GUDE: LIST OF HELICOII) LAND SHELLS. 45 



some even near to the month itself. I am thus led to believe the fourth 

 aperture is in some degree employed as an accessory food-providing organ. 

 I also observed that the orifice was constantly used f()r the purpose of eject- 

 ing water and foreign matter from the pallial cavity, especially if through 

 irritation the valves were suddenly closed, consequently I further think 

 that in E. siliqua and E. cnsis the fourth aperture acts in the dual capacity 

 of an accessory food-providing organ, and an exhalent orifice for ejecting 

 water or foreign matter, though the latter function is probably a secondary 

 one. In Lutraria ell I pt lea and Thracia papyracea, the fourth aper- 

 ture is situated at the anterio-ventral part of the mantle lobes. It is a 

 small orifice, has no tentacular fringe, is surrounded by the very strongly 

 developed muscles of the pallial edge, and is apparently under the control 

 of the animal. The labial palps do not come near it, being situated in the 

 anterior part, and the portion of the gills lying dorsally are a considerable 

 distance away, so that the aperture is not in close communication with 

 any other (>rgnn, ;.s in E. siiiqiia. Li'traria elliplira used the aperture 

 frequently in sudtlenly ejecting water or any objectionable matter from the 

 pedal cavity. When particles of carmine were placed close to it, they were 

 not drawn in, as in E. siliqva, the orifice only being used for ejecting water, 

 &e., and evidently not as an accessory food-providing organ. The origin 

 of the aperture is apparently of a different and more remote period than that 

 of E. siliqua. 



A CLASSIFIED LIST OF THE HELICOID LAND 

 SHELLS OF ASIA. 



(PART VI V) 



BY (!. K. (lUDK, F.Z.S. 



(Plate iii.) 



xiii. MALAY ARCHIPELAGO. 



The region now imder consideration possesses one of the richest and 

 most varied land molluscan faunas of the glol)e. The physical conditions 

 are eminently favourable to molluscan life, while the splitting up of the 

 region into inniunerable islands has contributed to the formation of local 

 races. The first naturalist to collect land shells hero was Rumphius, who 

 resided in Amboina, where he died in 1706 ; it was not, however, until 

 the beginning of the nineteenth century that the molhisca began to be 

 collected in a systematic manner. The first expedition was that of Baudin 

 to Timor in 1800-1804, and subsequent voyages were made by Freycinet, 

 Duperrey, Beechey, Dumond d'Urville, Yaillant, and Belcher, the results 

 being published in the various works dealing with the respective expe- 

 ditions. 



•See ante, p. 165. 



