338 F. A. Bather — On Hapalocrinus Victorice. 



The Eadials, five in number, appear to have been much wider 

 above than below ; but the intra-radial sutures are not clear, and 

 the appearance is no doubt due in part to the flattening of the cup. 

 The facet for the arms occupies about one-third the width of the radial. 



The Tegmen can be dimly seen, stretching up between the arms, 

 to a height about equal to that of the dorsal cup. It appears to 

 join on to the primibrachs, but is enough depressed between the 

 arms and distinct from the radials to be considered no part of the 

 dorsal cup. In other words, while the crinoid is not Inadunate, 

 neither is one of the highly developed Camerata. The number and 

 arrangement of the tegminal plates is not to be distinguished. 



The height of the calyx from its base to the top of the tegmen 

 is about 3 mm. 



The 5 Arms each branch once, on IBrg ; the total length is 15 mm. 



The 3 Primibrachs (IBr) are joined to the tegmen as far up 

 as the lower part of lAx. Their width is about -5 mm. ; the length 

 about half as much again. 



The Secundibrachs (IIBr), which begin by being slightly less 

 wide than the IBr, are about half as long again as wide. The width 

 gradually decreases to the end of the arm. 



Pinnules, alternating from side to side of the arm-branch, are 

 borne by each IIBr, except the first, and perhaps the second. The 

 facets for the pinnules are well marked, so that the long axes of 

 the IIBr form a slightly zigzag line. The greatest length of 

 pinnule observed is 4:'75 mm., its width being '125 mm. The 

 pinnulars appear to have been long. 



The Silurian and Devonian Platycrinid^. 



The monocyclic base, the simple and apparently symmetrical cup,, 

 the slender pinnulate arms, and the lofty tegmen prevent us from 

 seeking the relatives of this crinoid among the Inadunata (whether 

 Larviformia or Fistulata, Monocyclica or Dicyclica), the Flexibilia 

 of Von Zittel (=Articulata, pors, Wachsrauth and Springer), or those 

 Camerata in which the lower brachials and interbrachials form an 

 important part of the dorsal cup (e.g. Eeteocrinidge, Actinocrinid^). 

 Limiting our survey to the older Paleozoic crinoids, we see left 

 only a group of genera, which Von Zittel, in his " Grundziige der 

 Pal^ontologie," 1895, refers to the Larviformia and the Platycrinid^, 

 which Wachsmuth and Springer include in the , Platycrinidse, but 

 which Jaekel, in his fine " Beitrage zur Kenntniss der Pala30zoischen 

 Crinoiden Deutschlands " {Pal. AbhnndL, viii, Heft 1; Jena, 1895), 

 distributes among both his Order Cladocrinoidea and his Costata, 

 a Suborder of his Pentaorinoidea. 



Among the Silurian and Devonian representatives of this group are 

 Cordylocrinus, Culicocrinus, Coccocrinus, Hapalocrinus, Agriocrinus, 

 and Thallocrinus. These all agree in having a dorsal cup composed 

 of a pentagonal monocyclic base of three basals, one small and two 

 large, and a circlet of five radials unbroken by any anal plate. The 

 two primibrachs, though joined to the calyx wall by interradially 

 situated plates, stand out clearly from those plates, and likewise 



