PALEONTOLOGIC CONTRIBUTIONS ,117 



jachalensis. The more recent stratigraphic studies by 

 Stappenbeck of the Argentina Cordilleras have verified the dis- 

 tinction indicated by Clarke. 



Of the two species of starfishes here described, one is referred to 

 Encrinaster, a genus in Europe practically restricted to the Lower 

 Devonian, if we except a doubtful form from the Caradoc of Great 

 Britain. In America the Lower Devonian of Brazil has furnished 

 one species (E . pontis Clarke) and three species are here 

 described from the Devonian of New York, one each from the 

 Hamilton, Portage and Chemung groups. The combined occur- 

 rences of the genus in the Lower Devonian of Europe and Brazil 

 would indicate that the genus was well established in Lower 

 Devonian time in the European and South American seas, but 

 arrived in North America not until or lingered there until late 

 Devonian time. Its presence in the Lower Devonian of both 

 Europe and Brazil presupposes of course the possibility of its origin 

 or arrival there in late Silurian time. 



The second species is here referred to a new genus, Argentin- 

 aster. This has distinct relationship to the genera Hallaster and 

 Squamaster, the first of which is based on a species of earliest 

 Devonian age (Coeymans limestone), the second on a Silurian 

 species. Argentinaster may therefore indicate, if an inference 

 based on such slender evidence is altogether admissible, a late 

 Silurian or early Devonian age for the beds in question. 



Encrinaster yachalensis nov. 

 Plate 18, figures 1-5 



This Encrinaster from the Silurian of Cerro Blanco, Yachal 

 (=Quebrada del Aguadida) in Argentine Republic, collected by 

 Bodenbender, is represented by a single specimen exhibiting the 

 abactinal side. It is remarkable for two features, the very large 

 size of the disk and the very slender appearance of the rays, which, 

 however, is partly due to the fact that the adambulacrals seem to 

 have been rather thin and. are poorly preserved. The integument 

 of the disk is fairly granular and its margin is slightly concave. 

 Instead of the single row of marginal plates seen in other species 

 of Encrinaster, this species shows a great number of marginal 

 plates, owing to the fact that the marginal row is flanked on the 

 inside by two to three accessory series of plates which do not quite 

 reach the middle of the disk margin. While the large E . t i s c h - 

 beinianus (Roemer) shows a few accessory marginal plates 



