68 PATAGONIAN EXPEDITIONS I PALAEONTOLOGY. 



mandible and a number of isolated scutes of the carapace. The flask- 

 shaped figure is indicated either very obscurely, or not at all, and most 

 of the plates have no definite sculptural pattern, but are coarsely pitted 

 all over the exposed surface. The horizontal ramus of the mandible 

 tapers anteriorly less than in any of the preceding species and the sym- 

 physeal part, though very thin, is deeper vertically. In size, this species 

 slightly surpasses P. wnophorus and P. lagena. 



PAREUTATUS gen. nov. 



Premaxillary and corresponding mandibular teeth absent, giving the 

 dental formula f ; two rows of upper teeth nearly parallel ; all of the teeth 

 of elliptical shape, with long axis of ellipse directed antero-posteriorly, and 

 non-lobate ; grinding surface not displaying conspicuous alternations of 

 hard and soft dentine. 



PAREUTATUS DISTANS (Ameghino). 



Eutatus distans Amegh. ; Enumeracion sistematica, etc., 1887, p. 26. 

 Thomcotheriuni distans Mercerat; Rev. del Mus. de La Plata, T. II, 



1891, p. 45. 



Tlioracotherium crmntum Mercerat; Ibid. 



Proentatits distans Amegh. ; Enum. synopt. d. Mamm. Foss. de Pata- 

 gonie, 1894, p. 174. 



This species, which is known to me only from the specimens in the 

 Ameghino collection, an imperfect skull and some isolated scutes, has 

 teeth of such a different character from those of Proentatus as to forbid its 

 reference to that genus, to which, however, it is evidently nearly allied. 



The movable plates of the carapace have three longitudinal ridges, 

 which do not always extend to the hinder edge of the scute, but may be 

 cut off by a relatively broad, transverse, marginal ridge. The fixed plates 

 of the pelvic buckler, if correctly referred to this species, have a posterior, 

 nearly plane portion, on which the three longitudinal ridges are very 

 faintly marked ; this part is bounded in front by two oblique grooves, 

 which give it a wedge-shaped anterior termination. The anterior part of 

 the scute has five rather obscure figures, a larger median and, on each side 

 of this, two smaller laterals. 



The first upper tooth -, is separated from - by a slightly greater space 

 than those between the succeeding teeth, which are relatively small and 



