INVERTEBRATES. . 313 



First anal plate nearly twice as long as wide, pentagonal in 

 form, somewhat wedge-shaped, and deeply inserted between 

 one of the first radials and one of the subradial pieces. Above, 

 it connects on the left with another piece of about its own size, 

 resting upon a short truncated side of one of the subradials, 

 and connecting on the left with one of the first radials, while 

 its upper truncated side supports a third piece, the exact form 

 of which cannot be made out in our specimen. Both of the 

 anal pieces of the second range project more than half their 

 length above the summit of the first radials on each side of 

 them. Height, to the summit of the first radial plates, 0.14 

 inch; breadth, 0.50 inch; breadth of base, 0.14 inch. 



This species appears to be allied to Cupressocrinus impressus, of McCoy 

 {British Pal. Foss., pi. 3, D, fig. 2), which is a true Zeacrinus, but differs in 

 presenting a subhexagonal instead of a circular outline, as seen from below. 

 It also differs in having a smaller columnar facet, which only conceals a little 

 more than half of each basal plate, while in Z. impressus it seems to hide 

 the basal pieces entirely. There are likewise some differences in the.arrange- 

 ment of the anal pieces from those of McCoy's figure, but this is, as we believe, 

 due to his figure having been drawn on the stone without reversing the arrange- 

 ment of the parts. 



Our species seems to be also related to Zeacrinus mucrospinus, of McChesney 

 {New species palaeozoic fossils, p. 10, pi. 4, fig. 7), but it differs in having 

 proportionally much shorter subradial pieces, while the form of its first anal 

 piece is quite different. Its first radials likewise differ in being pentagonal 

 instead of heptagonal. Whether or not its second radial pieces are produced in 

 the form of long spines, as in Z. mucrospinus, we are unable to say, not having 

 seen any specimens showing the second radials. From its analogy, however, 

 to the species described by Prof. McChesney, we suspect it will be found to 

 possess similar appendages. 



Locality and position : Same as last. 



40 Sept. 20, 1866. 



