44 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.41. 



widespread structural feature. Hall in the tliird volume of the 

 "Paleontology of New York" describes some well-developed roots 

 as pertaining to Mariacrinus. This reference has slight evidence in 

 its favor, and such roots may well belong to quite distinct genera. 

 It is possible, however, that fixation by roots or terminal cementation 

 occasionally became effective, and may even have persisted the 

 greater portion of the animal's life. 



Woodocrinus. — In Woodocrinus macrodactylus from the Carbonif- 

 erous of England we have a type that unquestionably maintained a 

 free existence. A figure of this form is here given, plate 4, figure 3, 

 as copied from Zittel (1896), adapted from de Koninck (1854). 



It will be noted that the column is fairly stout in its proximal portion 

 and tapers rapidly distad. It is likewise quite short. There is no 

 evidence of attachment by cementation and there are no cirri in the 

 distal portion of the stem. The three cirri that are shown are located 

 well up on the column, and could scarcely have been effective for 

 purposes of permanent fixation. The distal portion of the stem 

 is not shown as being looped but from the manner in which the column 

 is flexed it would appear that this portion might well have been fairly 

 mobile, and possibly prehensile. The arms are stout, and though 

 short, might well form effective swimming organs. The cirri in 

 this form are of considerable interest. Though not sufficiently 

 specialized to function to any extent as prehensible organs, they 

 yet mark the tendency to be noted in all the detached stalked crinoids 

 toward the acquisition of such appendages. 



Glyptocrinus. — In the form described and figured by Miller (1880, 

 p. 233, pi. 7, fig. 3 a-c) as Glyptocrinus schafferi, which is almost 

 certainly the young of Glyptocrinus dyeri, we have shown a most 

 remarkable case of temporary attachment by means of a prehensile 

 column. This type seems further to elucidate certain structures 

 observed in widely divergent geological periods. 



In this species, as shown by figures 3h and 3c, the distal portion of 

 the column is found spirally coiled about the stem of an adult crinoid. 

 As described by MiUer the Glyptocrinus stem tapers distad until it 

 becomes remarkably tenuous. In its extreme distal portion it is 

 stated to be so small as scarcely to be visible to the naked eye. In 

 the specimen figured by Miller the column makes no less than seven 

 complete turns about the supporting stem. It is obvious, as sug- 

 gested by Miller, that the crinoid was a freely swimmmg form and 

 attached itself by will by wrapping the prehensile distal portion of 

 its column about some object. 



Unidentifiable spirally coiled columns. — In the Hamilton, Niagaran, 

 and at other geological horizons we are well acquainted with other 

 similar spirally coiled columns. In such cases, however, we have no 

 means of determining the identity of the crinoids. In many of these 



