386 PALEONTOLOGY OF ILLINOIS. 



spines. It therefore seems to be somewhat intermediate between the 

 D. Mississippiensis and D. quinquelobus, but is probably distinct specifi- 

 cally from them both. As we have but a single specimen, however, of 

 it, and the typical specimen of D. quinquelobus for comparison, we pre- 

 fer to place it for the present as a variety of that species, under the 

 name intermedius, and if it should hereafter be found that the differ- 

 ences we have pointed out are constant, it can take the name by which 

 we have proposed to distinguish it as a variety, as a specific name. 



Locality and position Upper part of the Burlington division of the 

 Lower Carboniferous series, at Burlington, Iowa. No. 164 of Mr. 

 WACHSMTJTH'S collection. 



GENUS AMPHORACKQs T US, Austin. 



As already stated, this group agrees with Actinocrinus in the number 

 and arrangement of the pieces composing the under side of the body, as 

 well as in having the parts adjacent to the arm bases forming five pro- 

 jecting lobes, distinctly separated from each other by the anal and 

 interradial sinuses. It differs from them both, however, in the struc 

 ture of the parts above, as well as in having the body generally more 

 depressed or even flat below, and the vault proportionally more ventri- 

 cose, while its second radial pieces are more generally hexagonal than 

 in Dorycrinus. From the latter it also differs in having the opening of 

 the vault more or less proboscidiform,* and placed nearly halfway 

 between the middle and the anal side, instead of being a simple gen- 

 erally lateral aperture, penetrating laterally a merely thickened pro- 

 tuberance. The proboscidiform extension of its vault, however, is 

 never so long and slender as we usually see in Actinocrinus, and also 

 often differs in being crowned with small spines surrounding the very 

 small terminal aperture, which seems always to open upward. As in 

 Dorycrinus, the vault is generally more or less spiuiferous, though 

 the spines are differently arranged, and, as far as yet known, never so 

 extravagantly developed as we sometimes see them in that group. 

 Some of the species are known to have one of the vault pieces over 

 each ray more or less protuberant, and it may be the case that species 

 existed in which those were developed into spines, somewhat as 

 in Dorycrinus, though we are not aware that any such have yet been 



* In all the foreign specimens of the typical species of Amphoracrinus that we have seen, only the 

 broken base of this short proboscis remains ; and this also seems to have been the case with nearly all 

 those from which the published figures, which we have had an opportunity to examine, were drawn. 

 CUMBERLAND, however, has given a figure in his Reliqua- Conservata? ( PL C), apparently of the typical 

 species amphora, with the short, oblique proboscis well preserved. This will be seen to differ ma- 

 terially from the merely slightly protuberant thickening in which the opening in Dvrycrinui; is sit- 

 uated. 



