210 SMITHSONIAN INSTITUTION 



distal divisions tapering rapidly and coiling inward over the tegmen to fine 

 points. Tegmen at a level a little above the last IIBr consisting of finely plated 

 calcified perisome, which passes down between the rays to a connection with 

 iBr plates. Column large, about as wide as the IBB ring; tapering from the 

 calyx for about a dozen diminishing columnals of equal thickness, there being 

 12 in a length of 7 mm. in a large specimen; from there the alternate columnals 

 begin to increase in length, and at a distance of 65 mm. are more than twice as 

 long as those interposed; the column gradually diminishes in thickness to an 

 unknown length and probably ends in one or more slender roots. 



Miller figured under the name, Cyathocrinites tnberculatus, two specimens, of which his 

 figure 2 is the distal part of an Ichthyocrinus piriformis. His figure 1 is a composite affair, 

 constructed from the calyx and arms of a specimen of this species with the stem of Sageno- 

 crinus added for greater completeness (PL XVI, fig. 1). I have a dozen specimens showing 

 more or less of the stem, and in none of them is it of the form shown by Miller's figure. The 

 species is exceedingly well marked, and when once understood is readily identified. 



The surface ornament is very characteristic, and need not be mistaken for that of any 

 other form in the Wenlock beds ; the tubercles of Ichthyocrinus pyriformis are much finer. 

 There is considerable variation in the intensity of the ornamentation, some specimens appear- 

 ing almost smooth ; this, however, is largely a matter of preservation. Looking at such a 

 specimen as figure 15, Plate XVI, with its widely-projecting wings or buttresses along the 

 margins of the rays, one would be inclined to think it a different species from most of those 

 on the same plate ; but the fact is that the same thing is found to a greater or less degree in 

 most of the specimens. Small angles or rounded nodes project in various sizes from the 

 lateral margins of the brachials just exterior to the line where the perisome joins them, but 

 usually these are not seen in an ordinary view on account of the depth of the plates. Figure 15 

 is flattened somewhat in a dorso-ventral direction, so that they can be better seen, but the 

 projections are also much more prominent in this than in any other specimen in the collection. 

 The actual structure is well shown in figure 3Z?, which is a detail enlarged from a specimen 

 of which the projections cannot be seen in the complete figure. 



The constancy in the number of secundibrachs in this form at three is interesting. In 

 23 specimens, of which 154 secondary arm-branches are exposed, only 12 vary from the 

 regular number — most of these being in one specimen which has seven out of eight visible 

 branches with 4 IIBr; in 19 out of the 23 specimens there is no variation. 



Roemer (Bronn's Lethaea Geognostica, vol. 1, p. 236) took this species for the type of 

 Cyathocrinus, which it is not any more than it is of Ta.vocrinus. Schlotheim referred it to 

 Encrinites, and Pacht to Dimerocrinites associating it with his Dimerocrinites oligoptihts 

 (now the type of Dactylocrinus). D'Orbigny referred it to Hall's Cnpulocrinus, now known 

 to be a transition form between the Flexibilia and the Inadunata. But Phillips recognized 

 its true affinities, and it has been treated by him and those following him who understood his 

 genus Taxocrinus as the best known representative of that genus, until I separated it in 1902 

 on account of the radianal. The structure of the anal side had never been understood until 

 then, while the relation between the anal and interbrachial plates and the perisome is now for 

 the first time described. 



Temnocrinus tuberculatns is one of the best known crinoids of the fossil beds at Dudley, 

 England ; it has always been much sought for 'by collectors, and specimens of it are found in 

 the leading paleontological museums of the world. In addition to Miller, it has been figured 

 by Schlotheim, Goldfuss, Murchison, Quenstedt, Pictet and Baily. 



Types. The original of Miller's figure 1 was formerly in the Ashmolean Museum at 

 Oxford, but like many other of Miller's types is now mislaid or lost. The original of my 

 figure 15 is in the British Museum, and the other specimens figured are in my collection. 



Horizon and locality. Silurian, Wenlock Group ; Dudley, England. 



