166 MESSKS. O. THOMAS AND H. SCHWANN ON THE [Feb. 20, 



p^, p"^, and m\ the missing teeth from the set of six possessed by 

 Helioj)hobius being tlie two posterior, m.^ and m^, pushed out as 

 it were by the poweiful roots of the incisors, which imjDinge on 

 them from below. 



This qu^estion could, however, only be conclusively settled by a 

 microscopic examination of foetal or new-born specimens, in which 

 traces of milk-teeth might be found, but in the meantime we 

 think the correct determination will be as here stated. 



" ' Blesmol ' of the Dutch. 



" Forms I'egular runs and mounds similar to other Moles, but 

 they can be distinguished by the size of the heaps thrown up." — 

 C. H. B. G. 



24. Georychus hottenxottus Less. 



(S. 1047, 1049, 1058, 1060. $. 1048, 1053, 1054, 1057. 

 Plettenberg Bay. 



The Mole-rats referred of recent years to G. hottentottus prove 

 on closer examination to be referable to tv/o species, a larger and 

 a smaller, of which the former is more northern and eastern, the 

 latter more southern and western in distribution ; but whether 

 and how far they overlap we are not at pi'esent able to say with 

 any certainty. The difference in size is chiefly in general bulk, 

 so that it is not easy to give any single dimension which will 

 distinguish the two at all stages, although perhaps the alveolar 

 length of the tooth-row (above 6'5 mm. in the larger, below in the 

 smaller) is as convenient as any. Restricting comparison to old 

 skulls only, the larger species may attain 36 mm. and over in basal 

 length, the smaller rarely reaching 33. 



With regard to names, it would appear that 7ioi^e7^to;{i^ts, ccecutiens, 

 and ludivigi are all applicable to the smaller species, but holosericeus 

 Wagn. may be applied to the larger. Thomas has seen Wagner's 

 three specimens, and found that the two "adults" are the large 

 species, and the " young " is the sm.all one. But as the measure- 

 ments given by Wagner appear to have been taken on one of the 

 larger specimens, that would fix the name on the latter. As to 

 locality, Wagner states that one of his specimens came from 

 Graaf Reinet, which might be taken as the typical locality. 



The following are the flesh-measurements of an old male 

 Plettenberg Bay example of G. hottentottus, the small species : — 



Head and body 142 mm. ; tail 15 ; hind foot 24. 



The adult specimens from Plettenberg Bay are of a very light 

 general colour, in marked conti'ast to those from Knysna, which 

 we have separated under a special heading. 



" Trapped in run in open country. 



" The runs and mounds of this species cannot be distinguished 

 from those of Amblysoraus corrice." — C. II. B. G. 



25. Georychus hottentottus talpoides, subsp. n. 

 S. 1067,1068. Knysna. 



Similar in essential characters to tiiie hottentottus, but colour 



