CRINOID GENUS SCYPHOCRINUS 23 



On p. yy, as a result of a general discussion of the species, they arrive at 

 the following arrangement : 



From what we have said it results that among the forms of Scyphocrinus there are 

 only three which can be exactly defined ; these are : 



1. S. subornatus Barrande. 



'var. zenonis W. and J. 



var. schlotheimi W. and J. 



var. typica W. and J. 



var. schroeteri W. and J. 

 3. S. decoratus Waagen and Jahn. 



2. S. excavatus Schloth. sp. p. 



As to the forms comprising no. 2 they say : " We are constrained to con- 

 sider them all four only as varieties of a single species, Scyphocrinus excavatus 

 Schloth." 



It will be observed that while in the last arrangement they place their 

 variety zenonis along with the other three in a specific group distinguished 

 from that of 6". subornatus, in the first arrangement, on p. 42, they consider 

 it as " differing notably " from those three. In my view of the relative 

 importance of the characters as elsewhere stated by them, it would be more 

 consistent to leave zenonis as a separate species, and perhaps to place decoratus 

 with the other three as a variety. 



Waagen and Jahn were much impressed by the singular conformation of 

 the interbrachial pavement, and through lack of understanding of its relations 

 were led to attach undue importance to its variations when disposing of zenonis. 



Conformably to the above suggestion, the following summary made from 

 their detailed descriptions and figures, as well as from my own observations, 

 will show the characters and relations of the Bohemian species; they are 

 taken in reverse order for better comparison: 



I. Group elegans: Calyx plates sculptured. 



Species 1. 5". elegans Zenker {excavatus W. and J., pars). 



Calyx elongate, obconical, of medium size to very large. Plates in 

 lower part low-convex, with several fine, continuous, parallel ridges of 

 costse radiating from near the center, crossing the sutures and connecting 

 from plate to plate, forming triangular or rhombic figures. Interbrachial 

 plates are not recognized higher than four ranges, it being considered that 

 above that they are so small, and their sculpture so strong, that it is difficult 

 to distinguish their contours, and that their arrangement is generally 

 irregular. In the interbrachial areas from about the zone of the first 

 secundibrachs the ridges either tend to coalesce into single, strongly raised, 

 wide or narrow bands crossing the sutures with sunken areas between, 

 giving a more or less reticulate, cancellate, stellate, or transversely banded 

 appearance ; or they may disappear, leaving the plates of the pavement 

 smooth or granular, flat or greatly rounded. These ridges are more con- 

 spicuous toward the margin of the plates, where they sometimes form a 



