326 SMITHSONIAN INSTITUTION 



WACHSMUTHICRINUS Springer 

 Plates XLIII, XLIV 



W achsmuthicrinus Springer, Amer. Geologist, XXX, 1902, p. 95 ; Jour. Geology, XIV, 1906, p. 510.- 

 Zittel-Eastman, Textbook Palaeontology, 1913, p. 205. 



%>3 



^3 ° 



^^ 



Fig. 43. W achsmuthicrinus 



Ichthyocrinidae with rays above radials separated in lower part by solid 

 plates, or in contact all around. Crown elongate, expanding from radials up. 

 Infrabasals entirely within ring of basals. Posterior basal not differentiated. 

 No radianal, or anal. Interbrachials present or absent; when present few and 

 variable, and the rays meeting above them. Primibrachs two. Arms heter- 

 otomous; rays in twenty main divisions, with simple ramules inside dichotom; 

 outside margins may interlock. Column large, expanding proximally. 



Genotype. Forbesiocrinus thiemei Hall. 



Distribution. Lower part of Lower Carboniferous; United States and 

 ( ?) Mountain limestone, England. 



This genus was proposed by me in 1902 for a type represented by several species which 

 differed from all other genera of the Flexibilia then known, with two exceptions, in the pen- 

 tamerous symmetry due to the complete absence of either anal or radianal plates. Those 

 exceptions are Metichthyocrinus and Nipterocrinns, which are so different in other respects 

 that their generic distinctness is apparent at a glance. W achsmuthicrinus may be called a 

 heterotomous Ichthyocrinus without a radianal, or, more exactly, a heterotomous Metich- 

 thyocrinus. Superficially it bears a close resemblance to the Devonian Synaptocrinus nuntius. 

 The pentamerism is very marked and constant ; in a considerable number of good specimens 

 only a slight deviation from it has been observed in a few cases where the posterior basal is a 

 shade larger than the others, and in an abnormal specimen in which two basals (which ones 

 cannot be ascertained) touch the first interradials (PI. XLIII, fig. 3). 



