108 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.41. 



Scytalocrinus. — In connection with the discussion of Agassizocrinus 

 should be noted a specimen of Scijtalocrinus which abnormally exhibits 

 similar structural features to those shown by Agassizocrinus. In this 

 specimen the column has been completely lost. Although disruption 

 from the column in this instance may be held to be abnormal, it may 

 well represent the effect of a tendency toward an eleutherozoic habit 

 becoming irregularly eifctive in this genetic line. Agassizocrinus is 

 closely related to Scytalocrinus and a condition so universally assumed 

 and maintained by this genus might well appear sporadically else- 

 where among related types. 



The specimen illustrating this unusual and interesting structure 

 has been described in Troost's recently published manuscript (1909, 

 p. 88) as Scytalocrinus (?) gracilis. Troost observed that the stem 

 is wanting and that there seems to be no evidence of stem attach- 

 ment. He therefore referred the specimen to the genus Agassizo- 

 crinus. Miss Wood, in editing the manuscript, referred the species 

 to Scytalocrinus, a genus to which it may well be referred. 



In this specimen there is no sign of fusion among the infrabasals 

 nor has a centrale been formed to plug up the axial canal. The 

 closing of this canal has been effected by a growth and close union 

 of the infrabasals themselves. The crinoid probably did not lose its 

 stem when young as Miss Wood supposes, A very definite flattening 

 of the infrabasals marks the former stem cicatrix, and while there 

 has been more or less resorption and solution there is every reason 

 to believe that the column had reached a fair size before the crinoid 

 became detached. 



The anal side of the crinoid is badly weathered, and it is somewhat 

 difficult to make out the true nature of the plates. Miss Wood in 

 her notes has pointed out that one of the infrabasals seems smaller 

 than the others and apparently does not reach the center. The 

 infrabasals were undoubtedly nearly equal in size, but o'\\'ing to 

 weathering one has been nearly eliminated. This shows how difficult 

 it is to judge accurately of the relationsliip of the other plates on 

 this side. The plates certainly are not "much distorted." The 

 left posterior radial seems abnormally small, and it is possible that 

 the left posterior arm was partially aborted. Not enough remains 

 now to be sure of this, however. The anal interradius seems fairly 

 normal. The primibrachs of the left antero-lateral and right postero- 

 lateral raj^s are curiously flattened on the sides toward the anal 

 interradius, but this I attribute to weathering. 



Miss Wood has suggested that the crinoid lay flat on the bottom. 

 This explanation might well account for the apparent distortion and 

 abortion of the plates and arms of the anal side, but is so opposed to 

 the habits of the Crinoidea that one hesitates to accept it. The 

 conditions as we have them may be accounted for on the basis of 



