228 EDWARD W. BERRY 



As a matter of fact the writer showed in 191 7 that the Corocoro 

 rocks were of PHocene age^ and this age determination is fully and 

 completely established by detailed field studies made by Singewald 

 and Berry in 19 19, the results of which are now awaiting publica- 

 tion.^ 



The presence of true Upper Cretaceous in this region rests on 

 the species of Echinocorys or Ananychites described below (Figs. 

 1-3), for which I am indebted to Sefior Arturo Poznansky, of 

 La Paz. It is said to have been collected at Pefias, which is just 

 east of the southern end of Lake Titicaca in the Department of La 

 Paz, and 55 km. northwest of the city of that name. It was not pos- 

 sible for me to visit the locality, but there is no reason for doubting 

 its correctness since the specimen was newly collected at the time of 

 my visit to La Paz and must have come from the near vicinity of 

 the place named. 



The specimen in itself is of great interest since it is, to the best 

 of my knowledge, the first specimen of this interesting genus, so 

 excessively abundant in the Upper Cretaceous of Europe, to be 

 recorded from South America, and the third or fourth to be recorded 

 from the Western Hemisphere. It does not agree with any of the 

 numerous described species and may be called in honor of its 

 progressive collector Echinocorys {Ananychites) poznanskii sp. nov. 



It may be described as follows: Ambital outline elliptical, roun- 

 ded in front and somewhat narrowed behind. Profile (i.e. , transverse 

 section) subcircular, the apex broadly rounded. Peristome ellipti- 

 cal 7 mm. in length by 10 mm. in width, situated about two-fifths 

 back from the anterior margin, hence relatively larger and slightly 

 more posterior in position than is commonly the case in this genus. 

 Periproct posterior, subambital in position, large, elliptical in form, 

 with a length of 8 mm. and a width of 6 mm. The apical system 

 is largely obscured by calcitic incrustations. As near as it can be 

 made out it consists of four larger genitals and five smaller oculars 

 arranged as indicated in the accompanying sketch (Fig. la). The 

 plastron appears to have been smooth and to comprise the sixteen 

 plates shown in the accompanying sketch (Fig. ib), and is unusual, 



■ E. W. Berry, U.S. Nat. Mus. Proc, Vol. LIV (1917), PP- 103-64. 



2 Singewald and Berry, Bull. Geol. Soc. Am., Vol. XXXII (192 1), p. 66 (abstract). 



