M. Turner 141 



usually short and rounded. The face view of the guards of all the hooks 

 of the Coenurus from the rat, of C. cerebralis and C. serialis, is broad, and 

 in all it is wider in the small hooks than in the large. 



The small hooks of the Coenurus from the rat and of C. cerebralis 

 have quite long handles, which are tapering in both but those of C. cere- 

 bralis are more so than those of the Coenurus from the rat. The handles 

 of the small hooks of C. serialis are usually short. In the small hook of 

 the Coenurus from the rat and in C. cerebralis the axes of the guard and 

 handle meet at an angle of from 100°-110°. In C. serialis this angle is 

 from 130°-140°. All the handles bend somewhat dorsally, but as these 

 figures show, that of the small hook of C. serialis is much more curved 

 than those of either of the small hooks of the Coenurus of the rat or of 

 the small hooks of C. cerebralis. 



The differences in the hooks of the Coenurus of the rat of C. cerebralis 

 and of C. serialis that have been given above are true for the great majo- 

 rity of hooks. Yet, as has been mentioned, variation amongst the hooks 

 sometimes obscures their distinguishing features. For example several 

 small hooks of C. cerebralis have been found with short dorsally curving 

 handles, so that if they had been isolated when examined they would 

 have been diagnosed as small hooks of C. serialis as in this Coenurus the 

 majority of small hooks have dorsally curving handles. 



In my material the tissue of the cyst from the rat and of that of C. cere- 

 bralis contained numerous calcareous bodies, but they were absent in both 

 cysts of C. serialis. Hall says that in his examples of adult Taenia serialis 

 the calcareous bodies were extremely abundant. 



From the data given above it is evident that the Coenurus from the 

 rat is either a new species or a very atypical form of a known species. 

 A more definite conclusion than this is impossible owing to the scantiness 

 of necessary material. 



REFERENCES. 



(1) Burton Cleland, J. (1918). Presidential Address to the Royal Society of N. S. 



Wales, Sydney, May 1st, 1918. Issued Sept. 5th, 1918. 



(2) Hall, M. C. ( 1919). The Adult Taenioid Cestodes of Dogs and Cats, and of Related 



Carnivores in North America. Proc. of the United States National Museum, 

 vol. LV, pp. 1-94. 



(3) Megnin, J. P. (1880). Sur une Nouvelle Forme de Ver Vesiculaire. Jour, de 



FAnat. et Physiol, etc., Paris, vol. xvi (2). 26 mars. 1880. 



(4) Rallliet et Henry (1915). On Coenurus glomeratus in the GerbiUe. Bidlelin 



de Path. Exotique, 1915, vol. vin. 



(5) Shipley, A. E. (1908). Rats and their Animal Parasites. The Journal of Eco- 



nomic Biology, vol. ui, part 3, 1908. 



