404 PROCEEDINGS oF SOCIETIES. 
writer has in his possession a one-seventh on the improved model 
and can without hesitation affirm that it is superior in definition, 
and far superior in clearness and absence of fogs or milkiness, to 
any other objective he possesses, these comprising a one-sixth and 
one-eighth by Andrew Ross, a one-fourth and one-twelfth by Thos. 
Ross, and a one-sixteenth and one-twenty-fitth by Powell and 
Lealand ; all considered first rate by their respective makers.” 
March 3rd, 1875. 
H. C. Sorzy, Esq., F.R.S., President, in the chair. 
Mr. H. J. Slack made some remarks upon the organism jpre- 
viously exhibited by Mr. Badcock, and thought to be the same\as 
Bucephalus polymorphus of Von Baer, and believed to have come 
from a fresh-water mussel. Mr. Slack quoted abstracts and ex- 
hibited figures from Von Baer’s paper (in the ‘ Nova Acta’ of the 
Leopold Carolinean Academy of Bonn, for 1826, p. 570) which 
left no doubt on his mind of the identity of Mr. Badcock’s 
specimen with that described by Von Baer. 
Another species, Bucephalus Haimeanus, had been described by 
Lacaze-Duthiers in the ‘Annales des Sciences Naturelles,’ 4me 
série, tome i, who found the abdominal organs of oysters 
and cockles completely invaded by the sporocysts of this 
parasite. Other descriptions of this species had been published by 
Claparéde (‘Beobachtungen iiber Anatomie, u. s. w., an der 
Kiiste von Normandie,’ 1863), and Alf. Guard (‘ Comptes 
Rendus,’ Aug. 17, 1874). 
Mr. Badcock thought that the animal described by him could 
not be identified with Von Baer’s, though it might belong to the 
same class of animals, and stated that Professor Huxley, who had 
first suggested its identity with Bucephalus polymorphus, had 
since doubted this. 
Dr. G. W. Royston-Pigott read a paper “ On the Principle of 
Testing Object-glasses by the Coloured Images produced by 
Reflexion from a Globule of Mercury and on Eidola.”’ 
Mr. Wenham explained to the meeting a new ‘“ Method of 
Obtaining Oblique Vision of Surface-structure under the Highest 
Powers of the Microscope.” 
April 7th, 1875. 
H. C. Sorsy, Esq., F.R.S., President, in the chair. 
A paper by the Rev. W. H. Dallinger and J. Drysdale, M.D., 
on “ Further Researches into the Life-history of the Monads,”’ 
was taken as read. 
This paper completed the series commenced some four years 
before on “ The Developmental History of Monads.”’ Referring to 
the chief forms which they had observed successively at different 
times in the maceration of animal tissues, the authors remark 
that simple conditions of season and temperature may account 
