666 JOTTINGS FROM SYDNEY UNIVERSITY BIOLOGICAL LABORATORY. 



of the rest of the minute structure is so totally different from 

 what we find in other Cestodes that I think it cannot be correct ; 

 and there would be little advantage in attempting a detailed com- 

 parison. The mode of termination of the principal trunks of the 

 canal system by opening in fi'out in the ueighbourliood of the 

 sucking-grooves would seem to constitute an important difference 

 between Ligula as described by Donnadieu and the frog-parasite ; 

 the presence in the former of distinct though immature repro- 

 ductive organs is also an important distinguishing feature. 



The histology — as regards the cuticle, subcuticular cell-layer, 

 muscular fibres and " parenchyma " — is very similar to that of 

 such mature Tcenice as I have studied {T. expansa of the sheep, 

 T. crassicollis of the cat, Dibothriuni tnicrocejyhalum of the sun-fish 

 and T. sp., of the emu) ; but the arrangement of some of these 

 parts is slightly different. Thus the layer of circular muscular 

 fibres, which is well developed in mature Tcenim, is entirely absent 

 here in the scolex from Hyla aurea, and the longitudinal fibres do 

 not form the complete layer which they present in the former. 



The entire structure of the parasite indicates unmistakably its 

 Cestode nature ; and superficial resemblances, at least, indicate a 

 relationship with Ligula ; but what comparisons I have been 

 able to make between the two former as regards internal structure 

 seem to point to considerable differences. The discovery of the 

 mature worm can alone set at rest completely the question of the 

 affinities of this remarkable parasite. 



EXPLANATION OF PLATE. 



Fig. \. — Anterior portion of the Cestode parasite of Hyla aurea, magnifiecl. 

 From a preserved specimen. 



Fig. 2. — Portion of a transverse section, x 100. 



Fig. 3. — A portion of a similar section. x 800. cut, two-layered cuticle. 

 ep, 'epidermis.' p.m., parenchyma muscle, x, layer in which 

 the fibres end. l.m., longitudinal muscular fibres, cal, cal- 

 careous corpuscles. 



