NATURAL SCIENCES OF PHILADELPHIA. 257 



this each main branch bifurcates without much divergence of the subdivisions, 

 which are short and divided, so as to form together a bunch of small bifur- 

 cating arms, thus making altogether apparently not less than several hun- 

 dred small armlets, or ultimate division of the rays, to the entire series. 



The small armlets are all short, and form clusters at the extremities of 

 the divisions of the horizontally extended strong rays, where they curve up- 

 wards, and fold together in bunches like tlie fingers of a clenched fist. They 

 are each composed of a single series of small pieces, which are wider than 

 long, with a minute patelliform piece at the underside of each, as in Forbesio- 

 cri?ius. 



Interradials three or four to each space, with others above belonging appa- 

 rently more properly to the vault ; first interradial series hexagonal and rest- 

 ing in a notch between the upper sloping lateral margins of the subradials. 

 Anal series consisting of a single free row of very small pieces resting upon the 

 upper side of the largest subradial, so as to present much the appearance of 

 an abortive armlet. Surface merely finely granular, with the exception of a 

 small linear ridge along the middle of each armlet. (Vault unknown.) 



Height of body, exclusive of vault, O'SO inch ; antero-postericr diameter, 

 0*90 inch ; transverse diameter, 1*40 inch; greatest transverse diameter be- 

 tween the extremities of opposite rays, 4 inches ; length of each of the two 

 main divisions of each ray, - t>5 inch. Column at its connection with base, 0'2S 

 inch in diameter, and composed of pieces only O'Ol inch in thickness, or ten, 

 to the tenth of an inch. 



This species is related to Onychocrinus asteriformis = (Forbesiocrinus as- 

 tericeformis, Hall,) but differs in attaining a much larger size, as well as in. 

 having the two main divisions of each ray widely divergent and proportionally 

 longer, instead of nearly parallel. Again it differs in having thesubdivisions 

 and armlets much more numerous ; also in having always five primary radial, 

 pieces to each ray. 



If reliable characters should hereafter be found for separating generically. 

 Taxocrinus from Forbesiocrinus, it is possible the name of this species would 

 become Forbesiocrinus (Onychocrinus) diversus, unless equally good characters 

 may be discovered for separating the three groups generically. It is quite as 

 probable, however, that Forbesiocrinus and Onychocrinus may be both included 

 as subgenera under Taxocrinus, in which case the name of our species would, 

 become Taxocr,nus (Onychocrinus) diversus. 



Locality and Position. Burlington group, upper bed ; Burlington, Iowa. 



Granatocrinus Shdmardi, M. & W. 



Body elliptic-oval, the length and breadth being as about 07 to 44. Base 

 having the form of a nearly flat pentagonal disc, with modeyately prominent 

 angles ; columnar facet round, and a little more than half as wide as the base. 

 Radial pieces lanceolate oblong, or nearly three times as long as wide, most 

 projecting and slightly narrower at the lower extremity, nearly flat between 

 the pseudo-ambulacral areas, along the margins of which they project ab- 

 ruptly in the form of a prominent knife-like keel ; forming five-sixths the en- 

 tire length of the body, and each obliquely truncated on each side above, for 

 the reception of the interradials. Pseudo-ambulacral fields very narrow,*fex- 

 tending the entire length of the body, with almost exactly parallel sides ; 

 rather convex, and each with a moderately distinct, longitudinal mesial linear 

 furrow, on each side of which about 65 pore pieces may be counted ; lanceo- 

 late and supplementary pore pieces unknown. Interradiali p.ioces about one- 

 fourth the entire length of the body, rhombic in outline, on widest in the 

 middle, and tapering nearly equally to the upper and lower extremities ; all 

 rather distinctly sloping inwards from the lateral angles to the middle, so as 

 to present a notched appearance on the outer surfaces. (Openings of the 

 summit unknown.) Surface showing, by the aid of a good magnifier, in a, 

 cross light, microscopic longitudinal lines near the lower end of the radial 



1866.] 17 



