164 WALKER-ARNOTT, ON ARACHNOIDISCUS. 
may be given, the more especially that Hupleuria incurvata 
(my original Gephyria) may be removed here. The costi 
are about 6 in ‘001 in the Ichaboe species, while in the 
Mauritius one they are much closer, 15 im ‘001. This last 
may be called Geplyria Telfairie, after the late Mrs. Telfair, 
who discovered the Alga in which it occurs. In this the ex- 
tremities of the frustules are sharp; but I have, apparently, 
the same species from the West Coast of Australia (obtained 
by washing some Alge collected by Mrs. Drummond, and 
sent me by Dr. Harvey), but in that the frustules are more 
obtuse. 
In my former paper I described Amphiprora Ralfsit ; mm the 
same number (‘Trans.’) is a paper by Dr. Donkin, to which 
I find it necessary to allude, on account of the want of 
courtesy there shown (p. 33). When I transmitted my notes 
to Professor Smith, Mr. Ralfs, or others, they were to be 
held as mere notes ; and although any gentleman is at liberty 
to see them, or to use them, after verifying them, all that I do 
not myself publish must be regarded as private communica- 
tions, and with which my name is not to be connected, if 
published by others. Dr. Donkin gets some information 
from Mr. Roper, and Mr. Roper gets his from Dr. Mont- 
gomery, and Dr. Montgomery gets his from Mr. Ralfs, who 
gave a slide, with a name attached, which name I have now 
published. But I beg to say that Mr. Ralfs’ side was not 
from material discovered by me, as Dr. Donkin asserts, and 
that the identification of Dr. Donkin’s Plewrosigma rectum 
with my Amphiprora Ralfsii, was not made by me. If Dr. 
Donkin wishes to know what my species is, he must not 
go to a slide named by others, or by myself, containing 
several objects, but to my specific character,* for in drawing 
it up I had reference to several forms, both in Mr. Ralfs’ 
gathering and found elsewhere; and any one may see from 
it that several of Dr. Donkin’s supposititious species are 
combined under that character; im fact, Mr. Ralfs’ gathering 
contained, so far as I can comprehend his descriptions and 
figures, Pleur. rectum, Wansbeckii, minutum, and probably 
also angustum, which I consider one and the same species of 
Amphiprora. Pleur. carinatum I ought perhaps to add to the 
list, for I believe that the striz only appear oblique in con- 
sequence of the position of the light; if a true Pleurosigma it 
may be Pleur. obscurum, the only one with that peculiar ap- 
* T might have made the diagnosis more precise by saying the valves, 
although carinate, are not alate. This, however, is implied by not. noticing 
an ala. 
