108 PROCEEDINQS OP THE ACADEMY OF [188fi. 



plate al)iits against the two posterior radials; it is large, 

 heavy, somewhat elongate, and surrounded anteriorly and later- 

 ally by what may prove to be four proximals (?). The' inter- 

 radial plates appear to be small, but may be pai'tly hidden from 

 view by the large covering plates. 



The form of the column is not known, but it was, like in 

 Cupressocrinus, perforated with a central canal and four per- 

 ipheral ones, which were confluent at the centre. 



Geological Position, etc. Confined to the Devtmian of the 

 Eifel. 



The following species have been described : 



18;i8. Gasterocoma antiqua Qoldf. (Type of the genus), Nova Acta Ac. Leopold. XIX, 



i, p. 96. Pictet, 1867, Traite de Pallont., iv, PI. C, fig. 7. Schultze, 1866, 



Echin. Eifl. Kalk., p. 96, PI. 12, fig. 1. Devonian. Eifel, Germany. 



Si/n. Epactocrinus Irregularis Mliller (Wirtgen and Zeiler), 1855, Verb, 

 naturh. Verein. f, Eheinl., xii, p. 85, PI. 12, figs. 5-8. 

 1866. G. gibbosa Schultze, Echin. Eifl. Kalk., p. 98, PI. 12, fig. 5. Devonian. 



Eifel, Germany. 

 1866. G. MuUeri Schultze, Echin. Eifl. Kalk., p. 99, PI. 12, fig. 2. Devonian. 



Eifel, Germany. 



Si/ii. Ceramocrinus eifliensis Miiller (Wirtgen and Zeiler), Verb, naturh. 

 Verein f. Rheinlande, xii, p. 83, PL 12, fig. 2. 

 1866. G. reticularis Schultze, Echinod. Eifl. Kalk., p. 99, PL 12, fig. :L Devonian. 



Eifel, Germany. 

 1866. G. Stellaris Schultze, Echin. Eifl. Kalk., p. 10(1, PI. 12, lig. 1. Devonian. 



Eifel, Germany. 



NANOCRINUS Miiller. 



1856. Miiller, Moiiatsber. d. Berl. Acad., p. 355. 



1857. Miiller, Neue Echinod. Eifl. Kalk., p. 249. 

 1866. Schultze, Monog. Echin. Eifl. Kalk., p. 102. 

 1879. Zittel, Handb. d. Palaeontologie, i, 364. 



Nanocrinus is very closel}' allied to Gasterocoma, and had not 

 Schultze found six specimens which all have the same irregular 

 structure, we should feel inclined to regard it an abnormal form 

 of that genus. According to Schultze, the genus has five basals, 

 but only four radials ; the place of the fifth one is said to be 

 occupied by an interradial. The latter is strictly radial in [)Osi- 

 tion, and as such should be designated as a non-arm-bearing 

 radial. 



Generic Diagnosis. Basal cup as in Gasterocoma, but the 

 plates less regular; four of them pentagonal, the posterior one 

 considerably higher, hexagonal, truncate above. 



