280 PAL.EONT0LOGY OF NEW-YORK. 



338. 2. HETEROCRINUS SIMPLEX. 



Pl. LXXVI. Figs. 2 a, b, c, d. 



Body slender, very gradually expanding above the base, and composed of five regular 

 divisions above the pelvic plates; pelvic plates five, four of them irregularly pentagonal, 

 and one wiih the lateral and upper margins equal ; costal plates in two of the divisions 

 single, hexagonal, and supported on the straight upper edges of the pelvic plates, those 

 of the three other divisions double, the lower one pentagonal with the lateral margins 

 short, the second one quadrangular ; scapular plates quadrangular, with the upper sides 

 concave and supporting a pentagonal arm-joint ; arm-joint supporting on its oblique upper 

 edges a double series of obliquely quadrangular or rhomboidal plates, which gradually 

 diminish in size ; column subpentagonal, composed ( near the pelvis) of alternating thicker 

 and thinner plates. 



This species is readily identified by its structure, which is peculiar in the form of four 

 of its pelvic plates, and the double or subdivided costal plates in three of the divisions ; 

 the body and arms, when closed together, present a slender subcylindrical form, scarcely 

 attracting attention, from their resemblance to a collection of small individual columns. 

 The small fragment of a column attached, which is crushed, can scarcely be characterized, 

 but it is clearly pentagonal. 



I am indebted to Mr. J. G. Anthony, of Cincinnati, for the specimen here figured. 



Fig. 2 a. The specimen, natural size. 



Fig. 2 4. A few joints of the columns enlarged. 



Fig. 2 c. Section of the same, which is flattened from pressure. 



Fig. 2 d. An enlarged figure, showing the structure of the body and arms of this species. 



Position and locality. In the soft shaly portions of the Blue limestone of Ohio at Cin- 

 cinnati, equivalent in position to the Hudson-river group of New-York. 



339. 3. HETEROCRINUS? GRACILIS. 



Pl. LXXVI. Figs. 3 a, b. 



This is a small slender species, with the body but little expanded, supporting long and 

 slender fingers, which are not fimbriated ; column pentagonal, proportionally large ; the 

 plates distant, not nodulose on the angles ; radicles numerous, jointed, diverging. 



This is a very delicate species, approaching in form and general appearance to the first 

 species ; but the plates of the body arc so far destroyed that their arrangement cannot be 

 determined. The angles of the column are not nodulose, as in that species, and this is 

 almost the only olnious mark of distinction. 



FijT. 3 a. The .specimen of the natural size. 3 h. The same magnified. 



Position and locality. This species occurs in the soft olive shale at Snakehill, Saratoga 



ijjjjg (State Collection.) 



