438 DR. C. I. FORSYTH MAJOR ON 



lower cheek-teeth ; the first superior was missing, and from the form of the alveolus it 

 is declared to have heen very small. " En haut il paralt y avoir eu cinq molaires ; la 

 seconde est plus etroite que chez les Lagomys et pour ainsi dire reduite a une seule lame 

 marquee en travers de deux plis d'email, de maniere a figurer presque trois croissants 

 concentriques ; les trois autres ont deux lames dont la premiere est simple, et la seconde 

 pourvvie des deux replis d'email de la dent qui precede, excepte a la cinquieme dent, 

 oil elle est plus petite . ." The lower teeth are said to be four in number, " par 

 absence de la derniere. Premiere tetragone divisee par deux sillons en deux cylindres 

 comprimes, dont I'anterieure plus saillante est aussi un pen plus large et la seconde a 

 en arriere un petit pli d'email partant de Tangle interne surtout evident a la derniere 

 molaire et s'effa^ant assez tard par la detrition. Ces cylindres sont moiiis comprimes 

 d'avant en arriere que chez les Lagomys, et leur disque de detrition est ovale oblong, 

 brusquement attenue en angle du cote externe, arrondi vers rinterne." 



From the later descriptions of Titanomys and from examination of originals, we are 

 enabled to refer Pomel's Lagodus to the former genus, and at the same time to appreciate 

 the accuracy of his description. But without this help and iu the absence of figures, 

 it becomes ditRcult to form an exact conception of the comj)licated pattern of the 

 upper teeth, from their necessarily too short characteristics by Pomel. Hensel, when 

 describing the teeth of Prolagus (his Myolagus), was on the look-out for allied forms ; 

 he gives in full Pomel's description of Lagodus *, but fails to see the curious relationship 

 existing betAveen the upper premolars of the former and all the U2:)per cheek-teeth of 

 the latter. 



The small enamel fold described by Pomel as starting from the internal angle of the 

 posterior lamina in the three mandibular teeth behind the first is the " Hinteransatz " 

 of H. V. Meyer's Titanomys. The relations of the latter to his Lagodus are not discussed 

 by Pomel ; he suggests tlie former to be probably the same as JProlagus sansaniensis 

 (Lartet's Lagomys sai/sa>riensis). 



Pomel's Ai)i2)hilagus rests on lower jaws ; he considers it to be a subgenus of Lagomys, 

 apparently because in both there are five lower cheek-teeth : " la derniere molaire " (in 

 AmphUagiis) " ties petite est cylindrique et caduque, en sorte qu'il ne reste souvent que 

 quatre dents a la machoire." The form of the anterior lower premolar is the same as in 

 " Lagodus " and Titanomy s, and very diff'erent from the premolar of Lagomys, a 

 character which at once suggests that "Lagodus" and AmphilagHs may be identical, 

 and that the absence of the small posterior apj^endage in the lower molars attributed to 

 Amphilagvs is due to the specimens being from older individuals than those assigned to 

 " Lagodus." 



In Bronn's ' Lethsea Geognostica,' Pomel's Lagodus is given as a synonym of 

 Titanomys visenoziensis on the authority of H. v. Meyer {'^Jide Meyer in litt.'). 



The second edition of the Zool. et Pal. fran^. (1859) gives good reasons for considering 

 Titanomys trilobus as the young of T. risenociensis. Of the last lower molar in particular 

 Gervais says: — "la derniere monire encore avec assez d'evidence un troisieme lobe, qui 



* Zeitschr. d. deutsclj. geol. Ges. viii. p. G&9 (lS5<i). 



