10 



Memoirs of the Indian Museum. 



[Vol. VII, 



(fig. ii, 1-3). In Cliondroccphalus the dentition is normal, though the right anterior 

 lower tooth is less distinctly columnar than usual. In V index the dentition is reduced, 

 but the double origin of the lower of the two remaining terminal teeth may often be 

 seen, especially in the right mandible of unworn specimens of V. agnoscendus. The anterior 

 lower tooth of the left side is more conical in this genus, with dorso-ventral rather than 

 antero-lateral compression, though that of the left side is still much broader than that of the 

 right ; and there is a more or less indistinct tubercle at the base of this tooth on both 

 mandibles. In Proculejoides all trace of the double nature of the two remaining terminal 

 teeth is lost, the anterior lower teeth of the two sides become still more alike, and the 

 tubercles at their base become more conspicuous. 



Of the genera with modified dentition in other families, Proculejus has teeth exactly like 

 -those of Proculejoides, and the only species of Publius known to me has teeth not unlike 



those of Y index, but has no trace on either side of the 

 third terminal tooth and has more markedly 

 asymmetrical anterior lower teeth. The teeth of 

 Proculus, the most striking of all these genera, are, 

 however, more puzzling. Superficially they usually 

 resemble those of Proculejoides ; but between what 

 would be the anterior lower tooth in that genus and 

 the large tubercle at its base there is ordinarily a scar, 

 lef: by the breaking away of a columnar tooth which 

 seems only to persist in imperfectly hardened 

 specimens. This columnar tooth (see fig. ii, 4) has 

 the form of the type of anterior lower tooth charac- 

 teristic of the American series ; and it is impossible 

 to be sure whether the tooth in front of it forms the 

 most anterior part of a single but highly complex 

 anterior lower tooth, or is a lowest terminal tooth, 

 reduced in size and situated behind and on the inner 

 side of the middle and upper terminal teeth as in the 

 Indo- Australian series. 



Fig. II. 

 /. Chondrocephalus granulifrons (Batrfc). 

 2. V index agnoscendus (Percheron). 

 S. Proculejoides chimpionl (Bates). 

 4. Proculus mniszechi, Kaup. 

 The parts of the mandibles in front of and 

 excluding the movable tooth, illustrating modi- 

 fications in the dentition of American Passalidae. 



The more typical American and Ethiopian forms can be distinguished from each other 

 by the presence of one or more pairs, respectively, of marginal tubercles between the 

 anterior angles of the head ; but this distinction does not at first sight appear to be of 

 universal application, since at least two genera, Mitrorhinus and Stephanocephalus, which have 

 been accepted as American, have the additional tubercles characteristic of African genera. 

 Zang, moreover, notes records of the American genus " Passalus " {=Popilius of the present 

 paper) from the Congo, Senegal and Madagascar ; and in the Van de Poll collection several 

 specimens of Pentalobus sansibaricus bear the record " Bolivia "; while of two specimens of 

 a new species of Erionomus, described below under the name E. trichostigmoides, one bears 



