42 The Ottawa Naturalist. [June-July 



right anterior radials. It is to be noted that this arrangement 

 is not in accord with the general habit of the Heterocrinidae 

 in which the right posterior radial and the right and left anterior 

 radials are usually the ones divided. All the plates of the cup 

 are thick and heavy with the upper edges of the radials strongly 

 inflected. The tegmen likewise was of fairlv heavy construc- 

 tion, but it is not clearly observable. 



The arms. The arms are stout and bifurcate heteronom" 

 ously: in life, they probably extended to a height of 50 mm- 

 above the cup. The three normal radials bear arms which are 

 inserted on a facet extending across the middle third of each plate. 

 The first primibrach (costal) is axillary: the second or third 

 secundibrach (distichal) is axillary: the third or fourth terti- 

 brach (palmar) is axillary. The arm-segments are somewhat 

 hour-glass shaped and the various branches are of unequal 

 strength. The arms lie in a curved position, which is probably 

 normal. There is some evidence of the occurrence of stout 

 pinnulae at intervals, but the specimen is too poorly preserved 

 to warrant remarks on their distribution. 



The right anterior superradial is badly broken but it 

 appears to have carried an arm which maintained its strength 

 to a greater height than the normal arms. This arm does not 

 appear to have arisen from a facet on the exterior face of the 

 radial as in the case of the normal arms. The left posterior 

 superradial shows no evidence of an arm but it is possible that 

 one is bidden under the left ramus of the right posterior arm 

 which lies across the top of the plate. It is certain, however, 

 that the left posterior radial did not bear an arm analogous with 

 the three normal ones. 



The anal tube. The anal tube is a very slender structure 

 about 1 .5 mm. thick: it shows three segments in a distance of 

 6 mm. The tube appears to have risen from the small triangular 

 anal alreadv mentioned. Owing to the imperfect preservation, 

 the interpretation of this structure is attended with doubt. 

 The coincidence of the supposed anal plate and this tube-like 

 structure seems to justify the orientation decided on. 



The stem. The stem is relatively large, having a diameter 

 of 7 mm. at its proximal end. In the 18 mm. exposed by the 

 specimen, there is little evidence of tapering distally. A quin- 

 quepartite arrangement is clearly indicated with the subdivisions 

 interradial in position and therefore continuous with the basals. 

 If Wachsmuth and Springer are correct in stating that the seg- 

 ments of quinquepartite stems alternate with the cup-plates of 

 the proximal row, then this form is dicyclic with invisible 

 infra-basals. The stem shows transverse elevated ridges at 



