210 LAND AND FRESnAVATER 



he places Ibyais of Heynemann after Austenia (type gi'jas, Bs.), 

 and includes in Ibi/cus 1. Jissidens, Heyn., the type, coupling it 

 with sikkimensis, as if they were one and the same species. There 

 is no authority to support this, and he went further than I had 

 done when I wrongly placed sikkimensis in Ibycus as a subgenus of 

 Girasia. 



Stoliczka, when writing on Sophina calias (J. A. S. B. 1871, 

 p. 256) and describing its progressive shell-growth makes some 

 instructive remarks, which are as applicable to genera as they are to 

 the individuals of a species, which, upon reaching a certain stage of 

 maturity, rests, and then commences a further increase of the shell, 

 thus altering its form materially. Thus it is possible that a genus A 

 may have its origin in the young form, while another, B, starts from 

 the more mature. 



I have also to notice the description (external character only) of 

 '•'■ Ibticus sikkimensis (G.-Aust.)=Jissidens, Heyn.," p. 106, taken 

 from a specimen in the British Museum without locality, "purchased 

 at Stevens." The specimens may or may not be the same as 

 O. sikkimensis, G.-A., type in my collection, with which it was not 

 compared, and of which the greater part of the anatomy had been 

 described, the radula proving to be absolutely different to that of 

 I.Jissidens (Vol. I. pt. vi. p. 2t^9) *. 



I cannot accept Mr. Cockerell's conclusions, based on this speci- 

 men : G. sikkimensis, G.-A,, stands, I consider, as a good species. 

 Neither can I accept the views put forward at the end of the 

 paragraph, which I give in full, especially regarding the generic 

 position of a Javan species : — 



'■'■Ibi/cusjissidens,ii-ejn.,'was very insufficiently described; but as it 

 agrees with sikkimensis in all known points and was from the same 

 neighbourhood, though at a higher altitude, there seems no reason 

 for regarding it as distinct. Heynemann's name has priority." 

 A comparison of Heynemann's drawing of the radula and my 

 description of that of sikkimensis was never made when this was 

 written. Quoting further : " Ibycus, as a generic title, may perhaps 

 be used for a large series of forms allied to fissidens, including 

 pupillaris (Hurab.) from Java. Limax problematiciis, pi. viii. f. 

 flgs, 13-17, belongs to Ibycus, and seems allied to sikkimensis." 



As to Ibycus siamends (p. 107), this must be put in some other 

 genus when the anatomy is examined. I have seen the specimens 

 in the Natural History Museum, and came to the conclusion they 

 had no affinities with Africarion ater. In the ' Proceedings of the 

 Zoological Society of London,' April 1891, p. 225, "On the Geogra- 

 phical Distribution of Slugs," the same author states, commencing 

 at the bottom of p. 224, what I consider cannot be supported on 

 our meagre knowledge o{ Ibjfcusfissidens,Y\z. that '■'■Ibycus occurs in 

 the Himalayas, in Siam, and in Java ; it also exists in Borneo if, as 

 I believe, the Parmarion baccarii and P. dorice of Issel (which are 



* Tn truth, so little is known of /. fissidens beyond its radula that it is quite 

 unsafe to place any species, certainly on external character, in Heynemann's 

 genus. 



