NATURAL SCIENCES OF PHILADELPHIA. 75 



four times as long on the outer side, as wide. Upper dorsal plate subtri^onal, 

 with the lateral angles a little truncated obliquely outward, about twice as 

 wide as high, and truncated about three-fourths its breadth above, for the re- 

 ception of the middle or dorsal arm ; more than filling the broad triangular 

 notch between the upper ends of the dorso-latcral pieces. 



Dorsal arm simple, and comi)oscd, above the first piece, of oblong pieces, 

 that are rounded on the outer side, and about one third longer than wide. 

 Lateral divisions of the rays supported on the superior latter sloping side of 

 each dorso-lateral piece, composed each of (as far as can be seen) five pieces 

 in a direct range, extending out laterally and curving around toward the ven- 

 tral side ; of these pieces the first is very short and does not support an arm, 

 while each of the other bears an erect arm above. Each of these lateral arms, 

 as far as can be seen, gives off a small division on the dorsal side of the third 

 piece above the base, while the main division of each bifurcates again on the 

 fourth piece above, the bifurcating pieces being a little tumid. All the arms 

 have a deep ambulacral furrow within. 



Pieces of the ventral side unknown. 



Length of base, 0-10 inch ; length of body exclusive of base 0-35 inch : 

 breadth do., 0-27 inch; length of arms 1 inch. 



This species is related to C. dactglus, Hall, but differs in having its dorsal 

 arm simple, instead of bifurcating ; and its lateral arms bifurcating first on 

 the third, instead of the fourth piece. From C. ventricosus, Hall, it also differs 

 in having the dorsal arm simple, instead of bifurcating, while its upper dor- 

 sal piece is distinctly shorter in proportion to breadth than in tliat species. 



If farther comparisons should show these forms to be generically distinct 

 from Calceocrimis, and Cheirocrinus is found to be tenable, this and the pre- 

 ceding species would have to be called Cheirocrinus Wachsmuthi and C. 

 Bradleyi. 



The specific name is given in honor of Mr. Charles Wachsmuth of Burling- 

 ton, Iowa, to whom we are indebted for the use of the specimens from which 

 the description was made out. 



Locality and position. Upper Burlington beds of Lower Carboniferous, at 

 Burlington, Iowa. Mr. Wachsmuth's collection. 



Genus GILBERTSOCRINUS, Phillips. 



Subgenus Goniasteroidocrinus, Lyon and Casseday, 1859. 



Syn. Trematocrinus, Hall, 1860. 



Goniasteroidocrinus tenuiradiatus, M. and W. 



The only specimen of this species we have seen is too much crushed to ad- 

 mit of a detailed description of the structure of its body. It evidently at- 

 tained a medium size, however, and has unusually long, slender, pseudo- 

 brachial appendages, or false arms ; while its subradial pieces are produced 

 into short pointed spines. Its false arms are each composed, near the body, of 

 a double series of alternating semi-elliptic pieces, which are joined together 

 by their straight sides, and each pierced by a small central canal. At a dis- 

 tance of about three or four pairs of these pieces from the body, each series 

 of pieces diverges from the other at an angle of about fifty degrees, thus form- 

 ing two very long, slender, rounded, gradually tapering branches, composed 

 each of a single series of round pieces, generally less than twice as wide as 

 long, with a small central canal. These pieces have their articulating sur- 

 faces radiately striated, and could not be in any way distinguished from the 

 joints of the column of many crinoids, if found detached. 



From Prof. Hall's species <?/;?m.s* (which also belongs to the section of the genus 



*As this species is neither the type of the genus Gilh'rtsocrinus, nor of the .subgenus 

 Goniasteroidocrinvs, the name iypus can only serve to confuse and mislead the student in 

 regard to tlie history and synonymy of the genus, and hence ought to be changed. 



1869.] 



