212 LAND AST) FRESHWATKR 



] am not seeking for faults ; for I know Mr. Cockereirs work lies 

 parallel to my own — that we are both working with the same end 

 in view. 



With regard to disagreement on the question of classification, it 

 has given me considerable pleasure to read the Appendix to the 

 ' Check-list of Slugs,' written by Mr. Walter E. Collinge : there 

 is so much valuable advice to be found therein. With Mr. Collinge 

 I have had in the past agreements and disagreements, and these 

 last I, for one, consider regrettable in a certain sense. But such 

 must crop up in connection with the work we are interested in : 

 agreement is impossible, when we consider the scanty material 

 there has been in hand to work upon. Malacologists are, in fact, 

 making a survey of a close, complicated, and difficult region : to 

 use a Survey simile, we none of us start from the same measured 

 base of thought, expei-ieuce, or eyesight and material. It is to be 

 hoped, when all errors are eliminated and apportioned, we and our 

 successors in this field of exploration will close on a base-line as 

 nearly equal as possible. The following lines by Mr. Collinge will 

 not, I feel, be out of place (p. 55) : — " This new system, which 

 I am pleased to observe is spreading to other departments of 

 zoology*, demands a knowledge of internal as well as external 

 morphology, and, as I have previously stated t, rightly refuses to 

 recognise inadequate descriptions or descriptions of sJielh apart from 

 the animal, or to acknowledge genera or species founded upon purely 

 external features ; in short, it demands that they shall be classified 

 and created ' upon the aggregate characters,' and not upon single 

 features "J. P. 56 : — " llecourse must therefore be made to the 

 anatomy. In the form of the various organs we find a permanent 

 and well-marked difference between one genus or species and 

 another. ..." I quite agree with the following paragraph : — 

 " Until Mr. Cockerell describes and figures the anatomical differ- 

 ences in his species of Slugs, I cannot accept them as valid. I 

 do not say that they are not so, as many seem to be very distinct, 

 judging from the external features, &c. ; but until I see structural 

 differences, not mere variations in the breadth of colour of some 

 single organ — differences which mark them off in the majority of 

 individuals from their nearest known ally, — I shall regard them as 

 doubtful." 



Petalochlamys, subgen. nov. 



Type, formosana var. hypograpta, Pils. & Hirase. 



Shell many-whorled, depressedly conoid, smooth, shining. Animal 

 with broad and elongate shell-lobes, quite separate one from the 

 other, more or less veined. No amatorial organ (a common 

 character in these Malayan and Australian forms). The marginal 

 teeth bicuspid, not serrate. 



Range. Formosa and New Britain. 



* W. F. Kirby, ' Nature,' LSOo, 10th August, p. 339. 



t ' Ooiicliologist,' 1892, vol. ii. p. 64, foolnofe. 



\ JlerllcT. Trans. New Zeal. Inst. 1892. vol. xxv. p. 158. 



