368 PALAEONTOLOGY OF ILLINOIS. 



Section (b). Species with arm-openings directed upward, and arin- 

 bases usually more in groups than in Section (a). Arms, so far as 

 known, 20. 



B. Nashvillce (=Actinocr. 1 Troost) ; also B. laura and B. sinuosus (=Ac- 

 tinocrinus. Hall), B. ccquibrachiatus (= Actinocrinus , McChesney), and 

 our B. asteriscus and B. trochiscus. 



2. Subgenus ERETMOCRINUS, Lyon and Casseday. 



Species with arms flattened and alate above, and generally number- 

 ing from 12 to 20. Proboscis or ventral tube excentric, usually slender 

 below, and sometimes swollen in the middle, and more or less bent to 

 one side. Vault usually depressed. Brachial pieces more or less in 

 groups, separated by interradial and anal sinuses. 



Batocrinus ( Eretmocrinus ) magnificus, Lyon and Casseday, and B. 

 (Eretmocr.) calyculoides, B. (Eretmocr.) remibrachiatus,* B. (Eretmocr.) 

 cliOj B. (Eretmoc.) matuta and B. (Eretmocr.) clcelia, Hall (sp), all de- 

 scribed under Actinocrinus by Prof. Hall. Also B. (Eretmocr.) Ver- 

 nueilianusfi Shumard (sp.) described under Actinocrinus. 



In all of the above species the arms have been seen, and are known 

 to possess the characters of Eretmocrinus. The following species are 

 believed to belong here, from the general appearance of the body vault, 

 proboscis, etc., though their arms have not yet been seen. They all 

 certainly belong to Batocrinus^ even if not to the group Eretmocrinus, 

 viz : B. corbulus, B. carica, B. oblatus, B. sinuosus and B. gemmifornris, 

 all described by Prof. Hall under Actinocrinus. Also B. urnceformis 

 and B. Hageri, described by Prof. McChesney under Actinocrinus. Also 

 our B. dodecadactylus. 



3. Subgenus ALLOPROSALLOCBINUS, Casseday and Lyon (=Conocrinus 



of Troost's lists.) 



Body distinctly conical, being flat below the arm-bases (which are 

 directed outward on a plane with the flattened under side), and pro- 

 duced upward to the central proboscis so as to bring the whole visceral 

 cavity above the arm bases. Branchial pieces stout. 



B. (Allopros.) conicus, B. (Allopros.) depressus, Lyon and Casseday, 

 described under Alloprosallocrinus. Also our B. ( Allopros. ) euconus. 



* Prof. HALL mentioned, in describing this species, that it has the characters of Eretmocrinus. 

 t This species has the arms less distinctly alate than the others, the transition from Batocrimts to 

 Eretmocrinus heing through this and the species Konincki. 



