Mr. T. D. A. Cockerell on Australian Slugs. 371 
I refer to the limited powers of migration among slugs the 
natural means only are intended. It is notorious that these 
are extremely limited. I give many instances of slugs being 
earried long distances (from Hurope to St. Helena, New 
Zealand, &e., for example) by artificial means. Also it may 
be observed that many species of shell-bearing mollusks 
have been carried quite as far; there is a whole crop of 
synonyms originating in European species taken to the 
antipodes. 
(4). Mr. Hedley is of the opinion that Anettea Graeffei, 
Kreffti, and Schutet are one species. Any one may see by 
reading my paper that I doubted their distinctness: I say, 
““ Probably the number of species will be considerably reduced 
when they are better known.” Excellent authorities have 
considered them distinct, and I did not feel justified, with the 
material I had, in lumping them. The differences I observed . 
were not those between living and preserved specimens, but 
between specimens preserved in exactly the same way, and 
the alteration due to contraction &e., being a common factor,. 
need not seriously interfere. 
(5). Anettea Macdonaldi was named by Gray, who had 
New-Caledonian specimens; he supposed these the same as 
Macdonald’s unnamed slug from Aneiteum, but it has been 
since doubted whether this was the case. (As to this matter 
and the distinction of 7. Kreffti from its allies, see Mr. E. A. 
Smith, P. Z. 8. 1884, p. 273.) 
(6). Kkighteen species of //elécarion are on record from 
Australia; I do not say they are all distinct, but I am not in 
a position to reduce the number with certainty. When they 
have been shown to be less than eight in a satisfactory 
manner, it will be time enough to alter the statistics. 
(7). I did not say that Semper had not placed 4. Cumingi 
in Xesta. My point simply was that certain species, uswaliy 
placed in Helicarion, might be separated from it, at least sub- 
generically, It was not within the scope of my paper to go 
into further details, especially as the present state of know- 
ledge does not allow any approximately final subdivision to 
be made. 
(8). I quoted Parmella as a slug-like genus which is 
referred by authors to the Vitrina-group. I had “grave 
doubts”? myself, but could not go inte the details of the 
matter without unduly enlarging my paper. 
(9). I placed Cystopelta on the. characters given by Tate, 
who described it. Mr, Hedley examined a species, possibly 
not the same as Tate’s, found in Australia, and arrived at 
different conclusions. Admitting the weight of his remarks, 
