762 
PROCEEDINGS OF THE SOCIETY. 
Messrs. Ross & Co. also sent for exhibition examples of their 
“Eclipse” Microscope, with ring-stand, tripod-stand, and the rigid 
form. They also exhibited a Petrological Microscope, and a new pattern 
binocular stand. 
Prof. Bell said they had received, through Sir H. Trueman Wood, a 
copy of the Award of the Commission of the Chicago Exhibition. 
Mr. R. T. Lewis said he had placed under one of the Microscopes 
upon the table a slide which had been sent by Mr. Arnold W. Cooper, 
of Richmond, Natal. The objects mounted were some curious parasites 
found upon a penguin which was captured upon the sea-shore at Isipingo, 
a short distance south of Durban. Their general characters, especially 
the clavate antennae and palpi, seemed to place them in the family of 
Liotheidse, and the possession of two claws in this case would refer 
them to the genus Liotheum , but whether or not they were a new species 
had not yet been conclusively ascertained. If any of the Fellows of the 
Society present were able to recognize them, Mr. Cooper would be very 
glad to receive information. 
A note by Dr. H. Stolterfoth, “ On the genus Corethron ,” was com- 
municated by the Secretary. The paper was illustrated by photomicro- 
graphs, and also by slides exhibited under Microscopes in the room. 
Dr. Stolterfoth stated that he had carefully washed the material sent 
him by Prof. D’Arcy Thompson (from the Atlantic) so as to get the 
forms into pure water. <: I then burnt a number of preparations on 
the cover-glass, so as to preserve these delicate structures as much as 
possible in their original condition. As Count Castracane had expressed 
some doubt as to their siliceous nature, I boiled some of the material in 
sulphuric and nitric acid, and in this way proved their undoubted 
siliceous character. ... I have only been able to find one species, and 
that I have identified as Corethron criophilum Cast. This form varies 
much, both in appearance and size. From careful measurement, the 
length of the valve without the hairs varies from 1/150 in. to 1/100 in., 
but the greatest difference is in the breadth of the valves, which varies 
from 1/350 in. to 1/850 in. This difference in size is met with in many 
species of diatoms, and, when seen in all its varying proportions, in no 
way leads us to suppose different species. 
“ The generic definition given by Count Castracane is c Frustulia 
cylindrica, libera (?), valvis convexis, setarum radiantium corona cinctis.’ 
The query as to ‘ libera ’ I think may be omitted, as I have never found 
two valves united. In the forms I examined the connecting zones 
were smooth, and readily broke up into rings, seen in the slide prepared 
from boiling in acid. After I had burnt the material on the cover- 
glass, I mounted the slides in styrax, and from these preparations I have 
made five photographs illustrating the form and its structure. The 
mode of growth I have shown in a diagram, which demonstrates how 
from one valve the two new forms are developed, for the zone B falls 
away, and the hairs contained in the sheath spring out and furnish the 
hairs at the end of the new valves. . . . The direction in which these 
hairs lie is sometimes opposite, and, these forms being surface diatoms, 
