IKKDALE : LAND MOLLUSCA OF THE KEUMADEC ISLANDS. 375 



overlooked the fact that he subsequently corrected his own erroneous 

 conclusions. 



Whilst collecting I separated my shells into their apparent genera. 

 Unfamiliar with land molluscs, I was unaware of the subtleties 

 constituting the different groupings, and simply knew at sight 

 a ' Flaintnulhia ' by shell characters from a Cliaropoid, and knew 

 a Charopoid with an armed mouth was a Ptychodon. Attempting to 

 gain information I consulted tlie unquestioned authority, Pilsbry's 

 Guide to the Helices. I there found the family Endodontidae com- 

 prising Endodcnta and Flnmmulina, and that Endodonta covered 

 Ptychodon, Charopa, Phenacharopa, etc., these ' genera' being regarded 

 as sections only. The typical Endodonta seemed to sliow little 

 relationship as regarded shell characters witli my ' Endodontoid ' 

 forms, and I also observed that Pilsbry himself seemed to liave had 

 no little trouble in attempting to produce a satisfactory classification 

 of these minute forms. His final diagnosis of the genus Endodonta 

 reads: "Animal having distinct grooves above the margins of tlie 

 foot, but no caudal mucous gland." 



One of the few criticisms of this classification is that by MoellendorfE, 

 who, writing upon the Land Shells of the Caroline Islands (Journ. 

 Malac, vol. vii, p. 107, 1900), recorded the genus Flammulina. The 

 animal was dissected by 8uter, who observed: "the presence of 

 a peripodial groove, a caudal pore, the plaited jaw, and the radula 

 clearly indicate that it must be classed under Flammulina.'''' Moellen- 

 dorff therefore wrote : " As I have said elsewhere, I consider Pilsbry's 

 arrangement of including the well-defined family of Phenacohelicidse, 

 Suter (= Charopida;, Hutton) within his Endodoutidce as a regrettable 

 step backwards. The two families are not only conchologically 

 well distinguished, but have different types of jaw and radula, and 

 the PhenacohelicidjB possess a mucous pore . . . This (Sutcr's above 

 quoted) confirmation of mj- classification is interesting for two reasons. 

 Firstly, it proves that shell cliaracters are not by any means so 

 unimportant as modern malacology tends to consider them, and 

 secondly that the Phenacohelicidae extend much more to the Xorth 

 than hitherto known, the most northern habitat observed being New 

 Caledonia." It will be noted that both Moellendorff and Pilsbry 

 agree in accepting as a differential feature the absence of a caudal 

 mucous pore. 



I would now suggest that careful criticism of shell characters will 

 prove as beneficial to malacology as the premature grasping of 

 misunderstood animal characters. Thus, much as it displeases me, 

 I must call for reconsideration the presence or absence of a caudal 

 mucous gland as being of primary or even secondary importance. 

 The shell I hereafter name Ptychodon Royanm is a typical Polynesian 

 ' Endodontoid' in shell characters, and it covers an animal possessing 

 a well-developed caudal mucous gland in life. It is a tree-dweller, 

 and it should be noted that of the four discoidal forms living on 

 tree-trunks, from shell characters two are easily referable to 

 Flammulina, the third is the above-noted Ptychodon, and the fourth 

 is a typical Charopa. I would suggest that all four possess a caudal 



