TAXOCRINIDAE 345 



PROTAXOCRINUS Springer 

 Plates XLV, XLVI 



Protaxocrinus Springer, Jour. Geol., XIV, 1906, pp. 515, 519. — Zittel-Eastman, Textbook Paleontology, 



1913, p. 205. 

 Lecanocrinus, Billings (not Hall), Geol. Surv. Canada (Can. Organ. Remains), Decade IV, 1859, p. 46. 

 Taxocrinus, Angelm (in part), Icon. Crin. Sueciae, 1878, p. 8. 

 Taxocrinus (Gnorimocrinus) Wachsmuth and Springer (in part), Revision Paleocrinoidea, pt. 1, 1879, 



p. 50. 



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Fig. 46. Protaxocrinus 



Taxocrinidae with rays usually not abutting over interbrachials. Crown 

 elongate. Infrabasals low, taking small part in calyx wall. Posterior basal 

 elongate. Radianal in primitive position as infer-radial directly under right- 

 posterior radial. Anal tube-plates tending to sutural connection with right pos- 

 terior ray. Interbrachials few, or wanting; lower part of interbrachial areas 

 occupied by plates, or perisome, sometimes not appearing externally. Primi- 

 brachs two. Arms dichotomous, divergent. Column slightly enlarging next 

 to calyx. 



Genotype. Taxocrinus ovalis Angelin. 



Distribution. Ordovician, Silurian and Devonian; Gotland, the United 



States, and Canada. 



This genus includes the earliest known forms of the Crinoidea Flexibilia. It was pro- 

 posed by me in 1906 to receive those species with the most primitive anal structure — that is, 

 the radianal in form of a radial at the base of the right posterior ray ; among them are several 

 of Angelin's Taxocrini which Wachsmuth and Springer had separated under Gnorimocrinus. 

 At that time I was not fully aware of the structure of Billings's species Lecanocrinus elegans 

 and L. laevis, which are now seen to belong here and which carry the genus back to the 

 early Ordovician. Here we have in these two species, when compared with the Inadunate 

 genus Cupulocrinus from the same horizon and locality, a fairly close approach to the point 

 of divergence of the Flexibilia from the Inadunates, as already discussed. They show a 

 marked difference in habitus from the Silurian species in the condition of the infrabasals, 



