ieedale: land mollusca op the kermadec islands. 377 



the sub-genus Allodiscus of the genus Flammuh'na." Tlie species 

 indicated by Pilsbry are figured by Petterd & Hedley (Rec. Aust. 

 Mus., vol. vii, p. 288, 1909), and the shells called Fl. Rohlmi, 

 Petterd (pi. Ixxxiv, figs. 19-21), and Fl. ciiracoce, Brazier (pi. Ixxxiii, 

 figs. 14-16), have certainly an unfamiliar appearance wlien contrasted 

 with typical Flammulina. It might be noted that Hutton considered 

 Helix ide. Gray, such a typical Charopa tliat he cited it as the type, 

 whereas on account of anatomical features, including the possession 

 of a caudal mucous gland, it is included in Flammulina by Pilsbiy, 

 though a new sectioiuil name was bestowed upon it, viz. SiUeria, 

 to replace Patulopsis, Suter, preoccupied. 



I would endorse Pilsbry's dictum, above quoted, on tlie introduction 

 of Radiodiscns, and advocate the introduction of many new names 

 to be used generically in the family Endodontidee. Through the 

 kindness of Mr. J. H. Ponsonby I have been enabled to examine 

 many Australian Endodontids, and I note many of the forms of sliell 

 differ : and it would seem that examination of the apical features 

 might lead to a better understanding, since so far I have observed 

 that similar shell characters are subsequent to similarly constituted 

 protoconchs. I hope to have further to say on this subject later. 



Ptychodon Royancs, n.sp. PI. XVIIT, Fig. 10. 



Shell discoidal, spire not sunken, last whorl scarcely descending, 

 widely umbilicate. Whorls 4, in very old shells 5. Colour red- 

 brown, sometimes unicolor, sometimes flammulate with darker. 

 Protoconch consisting of one whorl finely sculptured with closely set 

 slanting radial threads, over sixty being easily counted ; adult whorls 

 with a sculpture of straight erect sharp lamellae, regular and 

 equidistant, between which are clearly marked minor threads. On 

 the first adult whorl there are about fifty regular lamellae with 

 a couple of minor threads between each ; the next has sixty lamellae, 

 more widely spaced, with generally three minor threads intervening, 

 and so on. Umbilicus deep and wide, almost one-third the diameter 

 of the shell, sides steep, exposing previous wiiorls. Apertuie lunate, 

 lip thin. Apertural armour: on the parietal wall are three long 

 prominent slender lamellae, two of which project so as to be observed 

 when the shell is viewed sideways and displacing five of the lamellae 

 of the previous whorl ; sometimes the third and lowest also is thus 

 observed, but generally it does not pass the outer lip. On the outer 

 lip are five lamellae ; two strongest agreeing in position with the two 

 major ones on the parietal wall, a third weaker agreeing with the 

 weaker parietal lamella, and two still smaller situated on the basal 

 curve; they can scarcely be said to be placed on the columella. This 

 description is drawn up from an old specimen with a max. diam. of 

 4 mm. The teeth vary somewhat with age, as a young shell shows 

 four well-defined parietal lamellae, a thin slender one occurring 

 between the two prominent ones above noted. Diam. max. 3"4, 

 min. 3 mm. ; alt. 1'5 mm. 



Hah. — Sunday Island, Kermadec Group. Living on the moss- 

 covered trunks of trees. 



