Lower Palccozoic Crinoids of Bohemia. 



105 



Beyrichocrinus humilis, the sole species of the genus, 

 conies from the limestone f 2 of Koneprus *. Only the cup 

 is preserved (Fig. 1). It consists of the following primary 



DAx 



.analia 



Fig. 1. 



-Analysis of the cup of Beyrichocrinus humilis, outlines copied 

 from Waagen and Jahn, and about twice nat. size. Inter- 

 brachiala (ilBr) and anals are shaded from right to left; 

 intersecundibrachs (illBr) from left to right ; intertertibrachs 

 vertically. 



elements : 3 basals, 2 large and 1 small ; 5 radials, which 

 appear to abut laterally by short sides, except in the posterior 

 interradius \ 2 fixed primibrachs in each ray, the first being 

 hexagonal except in the right and left posterior rays ; 2 fixed 

 secundibrachs in each half-ray ; 2-4 fixed tertibrachs, of 

 which the last is axillary and bore the free quartibrachs. 

 The secondary elements of the cup are : 5-10 interbrachials 

 arranged in 4-6 horizontal zones, the proximal interbrachial 

 resting on the steep shoulders of two adjacent radials and 

 coming very near to the basals ; in the wider anal inter- 

 radius are about 14 interbrachials (anals), of which the 



cup is an abuse." It is therefore perplexing to find the authors per- 

 sistently using the term in the sense they here deny to it. The fact is 

 that the word calyx has so often been used for the dorsal cup, that our 

 attempts to define it otherwise seem bound to fail. The adoption of 

 the term theca, as used by Haeckel, for the whole case or test con- 

 taining the central organs of the animal, seems the most rational escape 

 from the difficulty. 



The symbols and terminology of the present paper differ but slightly 

 from those explained in the Ami. & Mag. Nat. Hist. ser. 6, vol. ix. p. 57, 

 Jan. 1892. The nomenclature and classification follow Part III., The 

 Echinoderma, of ' A Treatise on Zoology,' edited by E. Ray Lankester : 

 London, 1900. 



* Oddly enough, the authors have adopted for the Bohemian names a 

 spelling different from that hitherto employed in the ' Systeme Silurien.' 

 Their reasons, though not given, are probably good enough to warrant 

 me following them iu this article. 



