RHODOCRINIDJE. 237 



from five to seven "long pendulous cilia" bearing delicate pinnules. The 

 pinnulated " cilia " they afterwards refer with a query to arms. 



Hall in I860, without making any comparison with Goniasteroidocmiis, 

 described under the new name Trematocrinus, a number of species from the 

 Subcarboniferous, of undoubted generic identity with Lyon's species. He 

 also regarded the upper appendages as arms, but doubted if they could have 

 performed the functions of arms. He further suggested that probably the 

 '' foramina " above the secondary radials served for the protrusion of " fleshy 

 arms or tentacles," However, a year or two later he described his Tremato- 

 crinus spinigerus with '' summit arms " and '^ true arms." 



In 1865, Rofe, who apparently was not acquainted with the w^ritings 

 of Lyon and Hall, while discussing certain morphological questions, asserted 

 that Phillips' species of Gilhertsocrinus '^ are undoubtedly Rhodocriiiir He 

 also stated that Rhodocrinus differs from most of the other Crinoids " in the 

 form of the arms and in the position of the ovarian apertures," and that 

 " the arms have no grooves on the upper side, but are cylindrical, with a 

 tubular canal through the axis, and the ovarian openings placed immediately 

 under the base of the arms." In reply to Billings' supposition that the 

 upper appendages might possibly be spines, he said : " their articulated struc- 

 ture, and the passage through the axis forbid the idea of their being 

 spines." 



Meek and Worthen, in 1866,^ discriminated between G-ilhertsocrimis and 

 Goniasteroidocriniis ; making the latter a section of the former. Gilbertsocri- 

 nus was said by them to have the " pseudo-ambulacral appendages " located 

 directly over the interdistichal spaces, and Goniasteroidocrinus over the inter- 

 radial ones ; and they stated that these structures are not arms, that they 

 '' differ essentially from all appendages of the body in any known Crinoid, 

 and seem to bear somewhat the same relations to the body, that the side 

 branches of the column of Pentacrinns and many Palseozoic Crinoids do to the 

 column itself." The 'Urue arms," they say, connect with the calyx at 

 the lower openings, which Hall described as foramina in Trematocrinns. 

 They gave a description and good figures both of the true arms and the 

 appendages. 



Grenfell, in 1875, defined Gilhertsocrinus as follows: " Basals fivQ-, sub- 

 radials five ; radials three ; brachials several, generally irregular ; the 

 second brachial channelled at top, and leading into an orifice which com- 



Geol. Rep. Illinois, Vol. II., pp. 219-221. 



