66 CONTRIBUTIONS TO AMERICAN HELMINTHOLOGY. 



small hooks were disposed at regular mtervals on the margin of the 

 rounded part of the disc. 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 Osier, 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. Fi'om some speci- 

 mens, in a good state of preservation, mounted by Dr. Osier 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 IS^ecturus 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 Yogt's^^ 

 figures and descriptions of D. sequans, 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, PI. XIII. 



26 Zeit fiir wiss. Zool., Suppl. XXX., Taf. XIV. 2, XVI. I. 



