New Species of Fossils. 211 



of the arms. In the right posterior ray, a pentagonal bifurcating plate 

 rests on the radial below, and supports the brachial plates on its 

 right sloping side above, and also a row of quadrangular plates on 

 the left side. These plates form an elevated ridge, and support two 

 thin, curved, broad plates that unite opposite the posterior ridge, 

 where there is a smaller ridge. These plates are concave between 

 their upper and lower margins, which gives a peculiar annulated 

 appearance to the anal tube. This is usually well preserved, and gives 

 a decided character to the species. The arms are slender and bifur- 

 cate frequently the plates constituting them all projecting at the 

 upper edge. 



This species is not uncommon at Trenton Falls, in the upper half 

 of the Trenton limestone, and is usually associated with Eeterocri- 

 nus simplex and H. laxus. 



Formation and locality. Trenton limestone, Trenton Falls, 1ST. Y. 



Genus DEJSTDEOCEINUS, Hall. 

 Dendkocrinus eetractilis, n. sp. 



Plate 17, fig. 4. 



Calyx small, obconic. 



Underbasals pentagonal wider than high. Basals hexagonal, the 

 posterior plate not showing in the specimens at hand. 



Radials broadest at the base, sloping a little from each side towards 

 the summit, those of the anterior and anterolateral rays pentagonal 

 and slightly wider than high. Six or seven brachials occur in each 

 arm to the first bifurcation. The posterior side of the body is con- 

 cealed, in the matrix. 



Arms long and slender, giving off, above the first bifurcation, at 

 intervals of nine or ten arm plates, divisions which are more slender 

 than the continuation of the arm. Although no pinnulse are to be 

 seen, in the specimen there is a small proturberance with a cicatrix 

 upon it on the inner side of each plate composing the arms. 



The lower portion of the anal tube is shown by the presence of 

 minute plates in the interbrachial spaces ; it continues up above the 

 plates as a compressed spiral, formed of a single series of elongate 

 narrow plates or joints which probably supported a tubular exten- 

 sion of the anal tube. That it was capable of being extended out 

 beyond the limits of the arms, is shown by its present position and 

 character. 



This species has a general resemblance to Dendrocrinus Dyeri, 

 Meek, but differs in the calyx and arms. 



Formation and locality. Trenton limestone, Trenton Falls, N . Y. 



