9 

 FOSSILS OF THE BURLINGTON GROUP. 385 



the rays, near so large. In the Mixsoiiricnxix the latter character is so 

 strongly marked as to place the widest part of the body above the arm- 

 bases, which consequently have the appearance of being attached half 

 way down the sides of the body, while in the species under considera- 

 tion the body is distinctly wider at the arm-base than above. Our 

 species has also seven or eight arms more than Dr. SHUMARD'S. 



Those who prefer to view the Dorycrinw group as only a section of 

 Actinocrinxx will, we hope, at least write the name of this species Ac- 

 tinocrinu* (Donjcrinux) Rcemeri. 



Locality and position Upper part of the Burlington beds of the 

 Lower Carboniferous series, at Burlington, Iowa. No. 127 of Mr. 

 WACHSMUTH'S collection. 



DOBYGREHTJS QUIXQUELOBUS, Tar. IXTERMEDIUS. 



PL 10, Fig. 4. 



Dorycrinug quintjuelobus, Tar. intermedius, MEEK and WORTHEX. Proceed. Acad. Xat. Sci., Pbila., 

 1868, p. 346. 



On comparing this form with the typical specimen of D. quinqitelobus 

 (=ActinocriHw qiiinqudobux, Hall, Supp. Iowa Geol. Report, Vol. I, 

 p. 15,) we find that it agrees very closely in the structure of its body, 

 as well as in the number of arm openings in each ray (that is, four to 

 the anterior and each posterior ray and two in each of the lateral rays), 

 but at the same time it presents some other differences, that we suspect 

 may be even of specific importance. In the first place it is larger and 

 more robust, and has a proportionally smaller base, and rather dis- 

 tinctly tumid, instead of even body plates, while its interradial and 

 anal spaces are not near so deeply excavated between the arm-bases as 

 in the type of quinqndobm. Its third radial pieces also differ in form, 

 being so narrow in all the rays as to let the secondary radials come in 

 contact with the first interradial and the second range of anal pieces, 

 instead of extending around so far laterally as to separate these pieces. 

 Its vault is likewise more flattened on top. 



In the typical specimen of D. quinquelobus the spines of the vault 

 have all been accidentally removed, but in the form under considera- 

 tion they seem to have been short and stout, though their en tire- length 

 is not known, as they were apparently broken off during the life of the 

 animal, since they each have the broken end somewhat rounded and 

 indented in the middle. In size and general appearance it is more like 

 D. Mixxiwippienxis of Rreiner, butit differs in having rather more tumid 

 body plates, as well as in the number of the arm openings, that species 

 having four of these openings to each ray all around. It also has a 

 more protuberant anal opening, and probably had much shorter vault 



