SAGENOCRINIDAE 219 



between the two half-way up; similar series of plates of correspondingly smaller 

 size and number fill the illBr and illlBr areas, likewise passing into the tegmen. 

 Anal area similar to the others, usually with an additional vertical series in the 

 middle, at least part way. Anal x not materially different from iBn, and not 

 larger than succeeding anal plates. RR the largest plates in the calyx; brachials 

 regularly diminishing upward to the arms, which become free in young speci- 

 mens about the upper IIBr, in older ones not until the next bifurcation. IBr 2; 

 IIBr usually 3, exceptionally 2 or 4. Arms, long, usually infolding over the 

 tegmen; rounded or somewhat angular on the back, deep, bifurcating in mature 

 specimens four or five times or more after becoming free, and extending to very 

 long, slender, closely coiled finials. Column large, without proximal enlarge- 

 ment, composed from the calyx down of short projecting columnals alternating 

 with shorter and narrower ones ; 6 pairs in upper part make a length about equal 

 to the diameter; composition of distal end unknown. 



Notwithstanding this is one of the best known fossils of the famous locality at Dudley, 

 there is no satisfactory type figure for the species. Miller's is a composite formed from the 

 arms of a Dudley specimen and the calyx of a Carboniferous Rhodocrinus ; this was after- 

 wards elaborated in Bronn's Lethaea Geognostica, table 4, figure 2. Phillips's specimen was 

 imperfect, being a crown minus the calyx below the upper secundibrachs ; but his figures are 

 sufficient, when taken in connection with the numerous good specimens now available for 

 study, to determine the form beyond any doubt. I have copied his principal figure, reduced 

 to the probable size of the specimen (PI. XVIII, fig. 1). The series of specimens from my 

 own collection which I have figured shows the species in almost every variation of age, size, 

 contour and surface preservation. The peculiar marking of the plates by concentric bands 

 shown in figure 9 is seen more or less distinctly in some other large specimens, and it may 

 have been a condition of mature growth ; the original of figure 3 has obscure traces of a 

 radiating marking on the plates, that of figure 4 a faint tubercular ornamentation. Not 

 enough constancy can be found in these appearances to warrant specific distinctions. 



Some variation in the position of the radianal may be observed in the specimens ; while 

 it is always in contact with the infrabasals, the relative breadth of its lower face varies, and 

 in figure 5 the radianal extends higher than usual between the radial and anal x, almost far 

 enough to separate them. There is also in some specimens a tendency of the first interbrachial 

 in the regular areas to pass down to a connection with the basals. None of the specimens show 

 any indication of the so-called " patelloid " processes, nor sinuous sutures, except slight traces 

 in the arms. 



Angelin recognized the species among the crinoids from the Wenlock beds of Gotland, 

 and figured three specimens, of all of which I have given new figures. It might be said that 

 the arms seem a little heavier in the Swedish specimens than in the English, and in some the 

 calyx relatively higher ; but the differences can hardly be defined specifically. 



Types. The original of Phillips's figures in the Silurian System is said by Murchison to 

 have been in the collection of Mr. Benjamin H. Bright, near Dudley, England, but I have 

 been unable to trace its present whereabouts. The other English specimens figured herein 

 are in my collection, and those from Gotland in the Riks Museum. 



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

 (horizon /), Gotland, Sweden. 



15 



