fF. B. Meek—Fossils of the Illinois Geological Report. 191 
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axocrinus Thiemei Hall; plate 1v, fig. 1—Although this 
beautiful crinoid seems to differ in some of its minor details of 
structure from Forbestocrinus Thiemei Hall, it is the form re- 
that as constituting a distinct venus, or as only a subgenus 
ert: ese two groups shade into each other by 
So many gradations, however, that it is not possible to divide 
the numerous species now known into two sharply defined 
genera ; as was shown by us in the Proceedings of the Academy of 
Natural Science in 1865, page 183, where we referred the 
Species Thiemei to the older genus Vaxocrinus. 
_ the great development and protuberance of the upper radial 
pleces in this crinoid, and the probably consequent drawing 
together of the parts above, give it a peculiar physiognomy, 
hot seen in the typical Zaxocrinus or Forbesiocrnus. Still it 
seems to show no differences of structure upon which it can be 
separated generically ; while, in the small number of its anals 
and interradials (the only point of difference between Taxocrinus 
and Forbesiocrinus), it agrees much more nearly with Taxocrinus, 
as may be seen by comparing it with Forbesiocrinus Worthent 
Plate X1v, fig. 2, and plate xv, fig. 7,+ which is a typical Furle- 
* If I remember correctly, F. Thiemei was described as being without either 
anal or interradial pieces. Smaller specimens, however, believed to be the young 
= the form we have figured, have been found, that were nearly or quite destitute 
jetradial pieces, and seemed to agree exactly with the description of F. 
+ The specimen from which these two figures were drawn was found loose, 
and was evidently water-worn, so as to have lost its surface granules, 
