66 CONTRIBUTIONS TO AMERICAN HELMINTHOLOGY. 
small hooks were disposed at regular intervals on the margin of the 
rounded part of the dise. There was ‘no trace of suckers. The small 
hooks had already attained their definitive size and form; the two 
large ones, on the other hand, situated considerably further in from 
the margin than in the adult, measured only 0.024 mm. instead 
of 0.15 mm. ‘This difference in length is owing to the shortness 
of the immersed portion, in which, however, the notch is already 
formed. 
It will be seen that in respect of the state of development of the 
large caudal hooks, this larva differs considerably from that of 
P. integerrimum. It is also larger, measuring 0.5 mm. in length, 
instead of 0.3 mm. 
SPHYRANURA OSLERI, nov. gen. et spec. 
I have lately received from my friend Professor Osler, of Mon- 
treal, several specimens of a worm taken from the gills and cavity 
of the mouth of our common Lake-Lizard (Necturus [Menobranchus] 
lateralis, Raf.) These had been preserved for eight years in Goad- 
by’s fluid, and proved comparatively useless for further examination, 
having become quite opaque and black in colour. From some speci- 
mens, in a good state of preservation, mounted by Dr. Osler for 
microscopical examination, and also from his notes and sketches made 
on observation of the fresh specimens, I am able to communicate the 
following. The only specimen of Necturus which I have had the 
opportunity of examining since receiving these did not yield any of 
the worms. 
According to Diesing’s conspectus (Revision der Myzhelminthen), 
the worms ought to fall into his genus Diplectanum. I have not 
access to Wagener’s later descriptions of the two species of this genus. 
It is evident, however, from a study of Van Beneden’s™ and Vogt’s™ 
figures and descriptions of D. eequans, that this form cannot be re- 
ferred to Diplectanum. It resembles Polystomum, and differs from 
Dactylogyrus and Diplectanum in the following points: (1) The size 
and shape of the egg; (2) the structure of the suckers; (3) the dis- 
position and number of the caudal hooks. It differs from Polystomum 
in the general form, the number of suckers, and the structure of the 
24 Rech. sur les Tremat. marins, p. 122, Pl. XIII. 
% Zeit. fiir wiss. Zool., Suppl. XXX., Taf. XIV. 2, XVI. J. 
