GODWIN-AUSTEN : IMPORTANCE OF ANIMAL IN LAND MOI.LUSCA. 4I 



which throws some light on the evolution of the family we are dealing 

 with. In the genera which compose the sub-family Macrochlamyifue, 

 viz. : Figs. 4 and 5, A and A\ — Macrochlainys; B\ — Euaustenia; B. — 

 Pamatella; G. — Syama;Yi. — Khasie/la; I. — Oxyies; K. — Bensotiia; 

 the retractor muscle of the male side of the genitalia is attached to 

 the periphery of a peculiar tightly wound coecum. In some genera, 

 such as Oxytes and Bensonia, this is hidden in a mass of muscular 

 tissue, partly concealing the coil. Its more general form is very well 

 exemplified in Macrochlamys hardwickei (A.), and it is invariably 

 present in both the large and the smaller species of the sub-family, 

 in fact it is its most distinguishing character. The exception to the 

 rule has occurred in two species from Sikhim, viz. : M. rhichilaensis 

 (Fig. 5 A) and M. zei/ioensis (Fig. sA^a). In the first the male organ 

 differs remarkably from that of typical Macrochlamys — the kale-sac is 

 very long, quite a flagellum, and close to where the retractor muscle 

 is given off there is a long free coecum openly coiled ; this undoubtedly 

 represents the closely wound coecum in the type species and the sub- 

 family generally, to the side of which the retractor muscle is usually 

 attached. In the other species, M. zemoeusis, the retractor muscle is 

 attached to the side of a free coecum, having a slight but open coil. 

 Other species will perhaps be found (an enormous number have yet 

 to be dissected) in which this character will occur, and I would sub- 

 mit this variation is indicative of the free coecum being the ancestral 

 and oldest form, the coiling being a subsequent packing away of 

 this accessory organ. This departure in form, as it were, in the 

 genitalia of these eastern Himalayan species, appears to me of 

 considerable interest in the gradual modification of special organs, 

 organs the function of which can only be guessed at. 



It shows (and it must have been a very slow process indeed) how 

 evolution has effected morphological changes in this family of land 

 molluscs, changes in the animal going on quite irrespective of changes 

 in the shell. In the genera I have referred to in this address, the 

 form of the shell is most variable, as many members of the society 

 know well, and a glance at the examples I have brought here illustrating 

 the genera will show this to those who are not so well acquainted 

 with them. 



In conclusion, I would beg the members of this society to consider 

 what a service they would be doing for our branch of natural history, 

 if they would preserve a few of the animals of the species they collect; 

 even some species of our own island fauna are not thoroughly known. 

 This applies with greater force to those who may go abroad, and to 

 those whose friends are collecting for them in distant quarters of the 

 elobe. 



