RHIZOCRINTJS RAWSONII. 31 



specimens to be crenulated like any other of the stem articulations. Grant- 

 ing, then, the absence of those pieces and using the nomenclature I have 

 adopted for the Ehizocrinus, the five basal pieces of Belemnocrinus are 

 formed precisely as in the former. The first radials, alternating with the 

 basals, are larger in Belemnocrinus, and are movable, whilst they are fixed 

 in Rhizocrinus. The next three joints are equal, and are properly brachials, 

 and are followed by an axial forming the bifurcation for the ten arms. The 

 stem has no resemblance to that of Ehizocrinus, being round or obscurely 

 pentagonal, and the articulations crenulated. 



