376 Bulletin American Museum of Natural History. [Vol. XXVII, 



superficial resemblances in the dentition Ameghino jilaces the Nothstylopidpe 

 near the Esthonychidtie, in the order Tillodontia; biit it appears much more 

 likely that they are connected more or less closely with the Albert ogaudryidae 

 or Homalodotheriidfe. 



The genera Hcnricoshornia, Trigouosiylop.s and Leontinia, which are the 

 types of as many families, are referred by Ameghino to different orders: 

 tiie first (1904, p. 511) to the Lemuroidea, the second (1904, p. 523) to the 

 Amblypoda and the third (1904, p. 525) to the Ancylopoda; but there 

 seems to be some reason for suspecting that all are more or less nearly related 

 to the common stem of the Homalodotheres and Astrapotheres. 



The Typoilicrcs and " Proti/pfjtheres." 



The Santa Cruz forerunners (Interatheriid;?, Hegetotheriida^) of the 

 Pampaean Typotheres have been monographed recently by Sinclair (Mem. 

 Princeton Expedition to Patagonia, Vol. VI, Pt. I, 1909), whose main 

 results were published in 1908 (op. cif.). The frequently assumed relation- 

 ship with the Rodents is shown by Sinclair (190S, ])p. 75-76) to rest on 

 probably convergent resemblances in the skull and dentition and to be 

 associated with many deep seated differences. Sinclair also shows that the 

 families in (juestion differ radically from the Hyracoidea especially in the 

 details of the carpus and astragalus, and it may be assumed provisionally 

 that the points of resemblance to Hyrax are the result of parallel evolution, 

 like the resemblances of Litopterns and Toxodonts to hippoids and rhino- 

 cerotoids; but at the same time it seems likely that in both cases the resem- 

 blances were conditioned by the fact that Hyracoids, Perissodactyls and 

 South American ungulates were all alike derived from one order of protungu- 

 lates (c/. pp. 410-411). 



In the preliminary report Dr. Sinclair does not discuss further the rela- 

 tionships of the forms in question, but presents the data for the following 

 observations and conclusions: 



(1) Protijpotherium, Interatherium and Hegetotherium. preserve the 

 complete Placental dental formula of Ixix- 



(2) The pattern of the unworn upper molar of Proiypotliervum Sinclair 

 {op. c/t., p. 7o) is seen to be a hypsodont, antero-posteriorly elongate modi- 

 fication, of a simpler pattern, e. g., such a one as is represented roughly in 

 some of the older (Xotostylops Beds) genera figured by Ameghino (e. g., 

 Accclodus oppositu-s, 1906, }). 311). The protocone is connected with the 

 parastyle, the protoconule with the "crista," which as in the Rhinoceroses 

 (cf. Hyrafhyus) is merely the constricted inner face of the paracone; the 

 hypocone, metaconule and metacone form the " postero-internal crescent," 



