336 PROCEEDINGS OF THE ACADEMY OP [1881. 



*18C2(?) Gennseoer. pooillum Hall. (Aotinocr. pocillum). 15th Rep. N.York. 

 St, Cab. Nat. Hist., p. 134. Hamilton gr. Western N. York. (Thid 

 speoiea probably belongs to some other gironp.) 



/. Batocrinites.. 



22. BATOCRINUS Casseday. 



(PI. 18, fig. 8 and PI. 19, fig. 2). 



1854. Casseday. Deutsche Zeitschr. d. Greol. Geaellsch., vi, p. 237. 

 1857. Pictet, Traite de Paleont., iv, p. 324. 



1865. Meek and "Worthen (Swbgen. Actinocr). Proc. Acad. Nat. Sci., 



Phila., p. 153. 



1866. Meek and Worthen (Subgenus of Actinocr.). Geol, Rep., 111., ii, p. 



150. 

 1869. Meek and Worthen. Proc. Acad. Nat. Sci., Phila., p. 350. 

 1873. Meek and Worthen. Geol. Rep., 111., v, p. 364. 



1878. Wachsm and Spr. Proc. Acad. Nat. Sci., Phila., p. 329. 



1879. Zittel (Subgenus of ^c^i/iocr). Handb. Palseont,,,p. 370. 



Syn. Actinocrinua (in part), Shumard, Hall, White, McChesney, 



Meek and Worthen (prior to 1865). 

 Syn. Uperoerinus. Meek and Worthen, 1865 (Subgenus of Bato- 



crinus. Proc. Acad. Nat. Sci., Phila., p. 153. 



The generic distinctions between Batocrinus and Actinocrinus 

 have been fully discussed in our remarks upon Actinocrinus, but 

 it remains yet to note the somewhat different mode in which the 

 arms increase in the two groups. We describe below two new 

 species of Batocrinus and three of Eretmocrinus, from which it 

 appears that in these genera, and in the Batocrinites generally, 

 the increase of arms, from one species to another, is not gradually, 

 by the addition of a single arm to each ray, as in the case of 

 Actinocrinus, but by duplicating the entire number of arms 

 throughout the species. 



Meek and Worthen in 1866, in adopting Batocrinus as a genus, 

 separated it into subgenera, and again subdivided the typical 

 form into two sections : " A, species in which the arm openings 

 are directed outward ; B, in which they are directed upwards, 

 and arranged, more or less, into groups." The position of these 

 openings had evidently no important bearing upon the general 

 structure of the crinoid, only that in the former the ambulacral 

 passages entered horizontally, in the others obliquely, and this 

 difference is caused by the greater or less degree of prominence 

 developed in the uppermost ring of radials. 



