250 PROCEEDINGS OF SOCIETIES. 
ing out these investigations I came upon rather an interesting 
structure connected with the iris, and which has not before been 
described; I call it the “posterior pillars of the iris.” Its 
attachments, where it runs into the anterior choroidal membrane, 
are by true tendinous fibres, and at their moment of origin they 
have a beautiful tree-like form. The preparations under the 
microscope show this. I have also here a preparation of the nerves 
of the iris, a fine plexus of nerves terminating in a true circle, and 
covering the whole surface of the iris like a fine network, which 
I have never before, I believe, seen in this country. Probably 
with a paper so technical many of the members present may not 
have felt sufficiently interested, but I shall be happy to show any 
one these preparations who takes an interest in them, or to afford 
them further information on the subject. 
Ten members were elected. 
Dusiin MicroscoricaL Curve. 
17th January, 1867. 
Dr. E. Perceval Wright (who was unable to attend) sent for 
exhibition, under Dr. Barker’s microscope, a specimen of 
Staurastrum gumidum from “ Callery Bog,” which (just at the 
boundary of the very dense and conspicuous gelatinous invest- 
ment, in itself characteristic of this species) was surrounded by a 
number of minute round green cells, each of these seemingly sup- 
ported on avery delicate linear stipes, reaching to the body of 
the Staurastrum. The radiant lines so often apparent in the 
thick gelatine investing the Staurastrum rendered it sometimes 
difficult to distinguish between them and the very delicate stipes 
of these bodies. They do not appear to be parasitic, as the 
Staurastrum was quite healthy and intact. The rounded cells 
eventually became detached and moved away as zoospores. 
Mr. Archer had found, from the same locality, and on the same 
occasion, several instances of the same species (Stawrastrum 
twmidum), as well as some other Desmids, being the bearers of 
this curious little plant. Sometimes, as in Dr. Wright’s speci- 
men above described, they cover the whole outer surface; at 
other times they were much fewer, and even only two or three 
upon a single desmidian: perhaps many of the green cells may 
have already disappeared from the latter as zoospores. There 
could be little doubt but that the present little alga, be its true 
affinity and nature what it may, was the same as that “ pin-like 
parasitic growth ” alluded to and figured by Dr. Wallich (‘ Ann. 
Nat. Hist.’, 1860, Plate VIII, fig. 5) as attached to a joint of 
Streptonema trilobatum. As to its affinities—temporarily admit- 
ting its right to a location like other forms which have not yet 
revealed any mode of reproduction except that by zoospores—its 
structure seems to point to Dictyospherium (Nag.). Dictyo- 
spherium Ehrenbergianum (Nig.) is composed of elliptic cells 
