F. G. Cawston 247 
various parts of South Africa. A comparison of the various schistosomes 
found in South African snails and of closely allied forms occurring elsewhere, 
of which particulars are appended, may be of interest to those who are engaged 
in the study of such parasites in South Africa. 
S. haematobium (C. criapa ) 
Approximate length 
of cercaria 
in mm. 
0-52 * 
S. mansoni 
(C. spinoaa't) 
0-39 
S. japonicum 
— 
0-5 
S. ? 
(C. indicae) 
0-39 
S. bo via 
(C. octadcna't 
0-43 
S. ? 
( C. oculata) 
0-35 
S. ? 
( C. secobii) 
0-55 
s. ? 
( C. (jladii) 
0-92 
S. haematobium 
( C. criapa) 
Testes in adult 
About 4 
S. mansoni 
( C. spinosa't) 
About 8 
S. japonicum 
— 
About 7 
S. bovis 
(C. octadena) 
— 
Pairs of mucin glands 
in cercaria 
3 acidophilic with large nuclei 
2 acidophilic with large nuclei 
4 basophilic with small nuclei 
5 acidophilic with large nuclei 
5 acidophilic 
2 acidophilic 
2 basophilic ? pharynx 
3 acidophilic with small nuclei 
4 all neutrophilic 
3 with small nuclei 
Ova in utero 
Numerous spine-pointed 
Usually one lateral-spined 
Numerous ova, practically aspinose 
Numerous spine-pointed 
REFERENCES. 
Cawston, F. G. (vii. 1917). The Cercarial Infection of South African Snails. Med. Journ. 
of South Africa, xn. No. 12. 
Cort, W. W. (1918). Adaptability of Schistosome Larvae to New Hosts. Journ. of Parasitol 
iv. 171-173. 
Ialst, E. C. (vi. 1920). Criteria for the Differentiation of Schistosome Larvae. Ibid vi 
192-194. 
(ix. 1920). A Survey of Cawston’s Species of S. African Cercariae. Parasitoloqu. xii 
212-216. 
(ix. 1921). The Present State of the Schistosome Problem. China Med. Journ. xxxv 
No. 5. 
Leiper, R. T. (18. iii. 1919). On the relation between the Terminal-spined and Lateral-spined 
eggs of Bilharzia. Brit. Med. Journ. 
Porter, A. (i. 1920). The Experimental Determination of the Vertebrate Hosts of some S. 
African Cercariae from the Molluscs Physopsis africana and Limnaea natalensis. Med. 
Journ. of South Africa, xv. 128-130. 
Soparkar, M. B. (vii. 1921 a). Notes on Some Furcocercous Cercariae from Bombay. 
Indian Journ. Med. Res. 
(vii. 1921 b). The Cercaria of Schistoso/nurn spindalis (Montgomery). Ibid. 
