1886.] NATURAL SCIENCES OP PHILADELPHIA. 183 



or of which one or both from the second plate branch again. 

 Arms massive, composed of short transverse plates, which in 

 their upward arrangement change from quadi'angular pieces with 

 strictly parallel sides to cuneiform and gradually interlocking 

 plates ; some of them, however, possess a fully developed biserial 

 arm structure. The union between radials and first brachials, 

 and also between the axillaries and pi'oximal arm plates is by 

 articulation, the apposed faces having highly developed facets 

 with transverse ridges, and a central canal and fossoe. The 

 two brachials are united by syzygy, as also the two proximal arm 

 joints. 



In Encrinus^ the inner floor of the dorsal cup is grooved by 

 five primar}^ canals, which, as they pass outward, bifurcate within 

 the basals, and the ten secondary canals thus formed proceed to 

 the radials, and thence after dividing again to the arms. These 

 grooves which are by no means restricted to Encrinus or to the 

 Neocrinoidea, are, according to P. H. Carpenter (his paper on the 

 Oral and Apical "system of Echinoderms, Quart. Journ. Microsc. 

 Sci. London, 1880, p, 362), passages for the fibrillar cords going 

 out from the interradial angles of the chambered organ. 



Nothing is known of the ventral surface, except in a young 

 specimen in which we thought to observe a few plates of a ventral 

 tube. The interradial plates, owing to the large size of the artic- 

 ular facets, must have been small at any time, and possibly were 

 absorbed in the adult. Column composed of circular joints with- 

 out cirrhi. 



Geological Position^ etc. Muschelkalk, Trias. Germany and 

 Switzerland. 



We recognize the following species : 



1847. Encrinus aculeatus v. Meyer, Lconh. Bronn's Jahrb., p. 576 ; also Palaeontogr. 

 i, 1851, p. 2G2, PI 32, fig. 1 ; also Beyrich 1857, Grin, des Muschelk., p. 38, 

 PI. 1, figs. 16 a, b. Muschelkalk, Trias. Upper Silurian, Germ. 



1850. E, Brahlii Owerweg, Zeitschr. d. deutsch. geol. Gesellschaft, vol. ii, p. 6; also 

 Beyrich, 1857, Grin, des Muschelk., p. 39, PI. 2. Muschelkalk, Trias. 

 Rildersdorf, Germ. 



1856. E. Carnalli Beyrich (Chelocrinus Carnalli), Zeitsch. d. deutsch. geol. Gesellsch, 

 p. 10; also Leonh, Bronn's Jahrb. (1856), p. 28. Muschelkalk, Trias. 

 RUdersdorf, Germ. 



1877. E. GrepMni De Loriol, Grinoides Foss. de la Suisse, p. 12. Muschelkalk. 

 Meyenbiihl, near Basle, Switzerl. 



