318 Annals of the South African Museum. 



We have been particularly struck in examining these specimens 

 with the special opportunities they offer for experiments on Men- 

 delian lines, and no doubt much satisfactory information would be 

 gained in that way. 



All the species noted in this account are characterised by very 

 small jaws provided with minute teeth which number about fifty. 

 In this respect they stand in marked contrast to Hirudo, in which 

 the jaws are very large and the teeth sharp. Furthermore, as in 

 Limnobdella, there is no muscular dilatation between the epididymis 

 and the base of the penis such as is found in Hirudo medic inalis. 



It seems to us that it is advisable that all species should be 

 described in such a way as to give information regarding the jaws, 

 genital apertures, number of testes, and male reproductive ducts. 

 Experience indicates that these should form the basis for a correct 

 classification of the Hirudininae. 



We hope to deal in greater anatomical details of the forms 

 described in a later paper. 



All the species noted possess seven dorsal black bands, which 

 differ only in regard to the prominence of any particular one in a 

 species. 



All are characterised by a yellow marginal band except H. scp- 

 temstriata, and the individuals examined in the case of the latter 

 species did not show the faint additional bands in the posterior 

 region of the body as figured by Grube. Yet as the bands other 

 than the median were very difficult to make out the absence of such 

 bands as mentioned may be only apparent. 



H. Morri&ii and H. notabilis agree in that the ventral and dorsal 

 surfaces are quite different, and the latter species has the rudimentary 

 pigment bands represented by Grube in his drawing of H. scptem- 

 striata. However, as the surfaces (dorsal and ventral) are similar 

 according to Grube, and no mention is made of the very prominent 

 marginal yellow band in H. septemstriata, there can be no confusion 

 in this case. The resemblance lends special interest to these two 

 forms, and if it has any significance at all bridges to some extent 

 the gap between H. septemstriata and the other species, all of which 

 bear the marginal yellow band. 



H. intermedia closely approximates to H. Hildcbrandti in that 

 both surfaces are alike, both possess a yellow marginal band, and 

 there is in each a dark marginal band on the ventral surface. The 

 latter in every probability represents the dark ventral surface 

 coloration of H. Morrissii and H. notabilis. H. capensis also 

 possesses a dark ventral marginal band. It is thus seen that all 



