376 PROCEEDINGS OF THE MALACOLOGICAL SOCIETT. 



mucous pore, whilst I should not be surprised to find tliat no ground- 

 living Endodont was possessed of such a feature. It should be 

 remarked that no Flammiilina was found permanently ground-dwelling, 

 and n)j' explanation of tlie presence ot a caudal mucous pore was 

 quite simple ! To the snails wliich had takcni up a tree-life a mucous 

 gland was a necessity, whiLst to tliose grouTul-dwelliug it would be 

 a luxury. Whether in tliese latter it had become aborted through 

 disuse, or in the former it had been developed through necessity, and 

 also the exact relationship of Flamnmlma and ' Endodonta\ 1 must 

 leave to the anatouiist to puzzle out. M}- own conclusions as to the 

 classification put forward by Pilsbry is that it was based upon too little 

 material, and too much value was given to a really insignificant 

 feature. Had more material been liandled it is ])robable that a tree- 

 livitig Endodont might have been included. As a matter of fact little 

 datiiage has been done, as, after a verj' few animals were dissected, 

 the molluscs were almost entirely grouped by means of shell characters. 

 Having thus mentioned the general classification 1 would deal with 

 the generic names Ptychodnn and Thaumatodon. 



Pti/chodttn was proposed for the Neozelanic leioda, Hiitton. In the 

 Man. Conch., ser. ir, vol. ix, p. 25, Pilsbry introduced Thaumatodon 

 as a section of Endodonta. Under this a large number of Polynesian 

 iind New Zealand snails are classed. No type is named, but as 

 muUilamellata, Garrett, is selected for illustrative ])urposes, I would 

 designate that as type. Now from the diagnosis of Ptychodun and 

 TJiaamaiodon given by Pilsbry, no differences can be observed, and 

 the two seem absolutely synonymous. If they can be maintained 

 from shell characters alone, a multitude of sections can be introduced. 

 But my criticism of Pilsbry's figures and description of muUilamellata 

 (1 have seen many specimens from Garrett's own collection, but none 

 agreeing with Pilsbry's account) leads me to recognize in it a close 

 relation, judging from shell characters, of my caudal mucous pore- 

 bearing Ptychodon, so that it is quite possible that 'Thaumatodon may 

 come into use for such forms. In the meanwhile it would be nuicli 

 better to drop Thaumatodon and refer to these armoured Charopas as 

 Ptychodon only. 



As I have noted, Pilsbry called all the Polynesian Endodonts 

 Endodonta, whatever their shell characters might be, and in this he 

 has been followed by most Australian and New Zealand writers. But 

 in 1906 he and Ferris introduced the genus Radiodiscus (Proc, Acad. 

 Nat. Sci. Phil., 1906, p. 154) for a shell from Arizona, and wrote: 

 " In the Endodontidse, where small differences in the shell characterize 

 extensive series of species, it seems desirable to recognize as generic 

 such readily definable groups as Radiodiscus.^' Later, writing on 

 the Non-marine Mollusca of Patagonia in the lleports Princeton 

 Univ. Exped. Patag., 1896-9, vol. iii, p. 516, 1910, this was 

 reprinted, and then was added — " Some Tasmanian snails have a great 

 resemblance to Radiodiscus in size, form, and sculpture, a resemblance 

 possibly due to convergence, but perhaps indicating affinity. I have 

 not been able to actually compare specimens. On account of their 

 spirally sculptured embryonic shells Hedley has referred them to 



