From the Niagara Formation. 



65 



CRINOIDEA.. 



Platycrinus silueicus n. sp. 



The base of the calyx composed of large plates, which have a 

 length of eleven mm. with a width of ten mm. The plates nearly 

 flat in the middle, becoming convex towards the margins, and abruptly 

 depressed at the suture line. Surface granulose, the granules 

 elongate, tortuous and confluent. 



Dendeocrinus ancilla n. sp. 



Body narrowly turbinate, width and height about as ten to twelve 

 or as ten to thirteen ; contracted between the arm-bases ; upper part 

 of the column closely adhering to the body, the five minute basal plates 

 scarcely distinguishable from the segments of the column at its summit: 

 subradial plates obscurely angular on the lower f ace,about three-fourths 

 as wide as long, very gradually expanding in width from the base, 

 and supporting on their upper adjacent sloping faces a large hexa- 

 gonal interradial plate, and this supporting a single radial, from 

 which the arms take their origin. Arms unknown. 



This species is narrower and less robust than longidactylus 

 {Pal. N. Y., vol. ii. p. 193, plates 42 and 43). 



Lampterocrinus parvus n. sp. 



Body small, somewhat narrowly turbinate, obtuse at the base 

 and obscurely pentagonal. Basal plates five, small; the subradials 

 larger : radial plates comparatively larger and strong, the third one 

 not determined : the first interradial nearly equal in size to the first 

 radial ; apparently two smaller plates above. Arm-bases prominent, 

 giving a distinct pentalobate aspect to the body ; the anal side ex- 

 tremely prominent. 



This species has the essential structure and general aspect of L. 

 Tennesseensis, except that there are fewer plates in the interradial 

 series, and the third radial plate is obscure. The specimen is much 

 smaller than any of the Tennessee specimens which have come under 

 my observation, having a height of only about ten millimetres. 



This species is from the limestone beds at Waldron, Ind. 



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