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PALEONTOLOGY OF NEW-YOKK. 



pelvic plates. The plates in the fingers of Lyriocrinus interlock somewhat more deeply, 

 and have a greater lateral extension and smoother surface than those of Glyptaster, 

 while the fingers themselves diminish more rapidly towards the extremities. From all 

 the other species of this period, this is readily distinguished on careful comparison. I am 

 the more particular in calling attention to the less conspicuous parts, since, in the larger 

 number of specimens seen, the structure of the cup is obscure, and it may not be readily 

 compared with the figures given on the plate. Many specimens have no portion of the 

 column remaining, and they appear like a globular sac with the simple terete arms 

 spreading above. The column is more like the column of Eucalyptocrinus than any 

 other species ; but the proportional thickness of the joints is less, and the projecting 

 edges of the alternate joints are much thinner. 



Fig. 1 a. An individual of medium size, preserving the cup and the arms nearly to tteir extremities. 



The structure is more clearly shown in this specimen, than in any other examined. Several 



of the arms remain imbedded in shale, and partly broken off. 

 Fig. 1 5. A smaller specimen, preserving a portion of the column, and leaving four of the arms only 



visible : the specimen is imbedded in shale. 

 Fig. 1 c. A larger specimen, showing the arms and column well preserved. 

 Fig. 1 d. The structure as made out from the specimen fig. 1 a. The commencement of three pairs of 



fingers is shown, and the simple joints at the base of the other pairs in the same relative 



position. 

 Fig. 1 e. A single plate enlarged, showing the character of the surface, and the increased ornament at 



the margins or junction with adjoining plates. 

 Fig. 1 /. A fragment of a column enlarged, showing more distinctly the alternating larger and smaller 



joints. 

 Fig. 1 g. The end of the column enlarged. 



Position and locality. In the shale at Lockport. 



