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Genus Belemnocrinus (n. g.) 



^elrfivov, a dart; Kqivov, a lily, in allusion to its resemblance to 

 a Belemnite. 



Generic formula. 



Basal pieces, five ; slioi't. 



Subradial pieces, five ; long, narrow, fisrming a cylinder wliich is 

 solid, except that it has a central perforation, and an excavation at 

 its upper end, forming part of the visceral cavity. 



Radial pieces, one ; large, x 5, and smaller ones, four, more or less. 



Anal pieces, one or more, the first situated between two of the first 

 radials. 



The position of the first anal plate is like that of Cyatlwcrinus, but 

 this genus, in the form and proportions of the body, diifers widely 

 from all others of the family. Its conspicuous features are its long, 

 solid, cylindrical body (the greater portion of which seems to have 

 performed the functions only of the column), the proportionally long 

 subradials and short basal plates, and the small visceral cavity. In 

 Agassizocrinus we have the nearest approach to these peculiar char- 

 acters of the body-plates, while in Zeacrinus we see the farthest 

 remove from them which the family presents. It is probable that in 

 Agassizocrinus the thickening of the lower plates of the body was the 

 result of an excrescent secretion of solid matter, which took place as 

 those soft parts of the body were absorbed which were no longer 

 necessary in the animal economy after its separation from the 

 column ; but in Belemnocrinus the thickening of the body-plates, and 

 the retreating upward of the vital parts, could not have been the 

 result of such a cause, as the column is well developed, and its com- 

 munication with the visceral cavity uninterrupted. 



The only known species of the genus is the following, which, from 

 the simplicity of its form, will probably be appropriately considered 

 its type, should other sjiecies be discovered. 



Belemnocrinus typus (n. s.) Body resembling a Belemnite, or 

 Belemnitella, in form, truncated at the base for the attachment of the 

 column, which is proportionally large, composed of alternating 

 thicker and thinner joints, with a small central perforation, round, or 

 indistinctly pentagonal at the upper end, where it has a diameter 

 nearly equal to the basal plates ; the sides sloping with gentle out- 

 ward curves to the column, with only a slight constriction at the 

 junction ; basal plates small, and not longer than the thickness of the 

 larger joints of the column, and from which they are not readily dis- 

 tinguishable ; subradial plates about four times as high as wide, form- 

 ing a slightly-inflated cylinder, smallest at the lower end, as solid as 

 the column, except that it has a slight excavation in the upjier end 

 which forms a part of the visceral cavity ; first radial plates about as 



