ORDER in C1UXOIDEA FISTULATA ir,:i 



convolutions in contact. Column strong, obtusely pentagonal, and quinque- 

 partite. Ordo\ ician ; North America. 



/"//////*, Hall. l> five, small : // five, the right posterior one compound. 

 Tin- lower section of tin- latter, which serves as radianal, nearly of the same 

 sixr as the other //, hut angulai above instead of concave. It supports the 

 superradial on the right, and the ventral sac on the left; it is so large as to 

 extend considerably above the level of the other //, thus assuming the aspect 

 of an axillarv hrachial. Ventral sac composed at its posterior side of a longi- 

 tudinal row of lame, solid, elongate plates; at the other sides of short, delicate, 

 transverse pieces; the former plates being attached to the It A, are -easily mis- 

 taken for arm ossicles. Arms without pinnules, branching. Column sharply 

 pentagonal ; the angles radially disposed. Ordovician ; North America. 



Herjicfu,rinn.t, Salter (Myoledactylus, trail). B five, of irregular form and 

 size. R five, the right posterior one horizontally divided. Ventral tube long 

 and narrow, and resting upon the sloping upper face of the inferradial. Arms 

 mm pinmilate, branching. Column evolute at its upper end, and more or less 

 round ; involute and crescent-shaped toward the terminal end, with large cirri 

 springing from the two horns of the crescent ; section sharply pentagonal. 

 Silurian : North America and Europe. 



Family 4. Belemnocrinidae. Wachsmutli and Springer. 



ic ; cylindrical to ovoid. It is composed of five large, elongate, 

 irregular pieces, ami is pierced by a small canal which widens slightly at the upper 

 ''IK!. Eadials five, quadrangular, and separated posteriorly by a narrow IRA. 

 I >' nf r<d sac large, composed of hexagonal plates, the angles of which are perforated. 

 .In us hit>;/, (j icing off armlets alternately at intervals. Column round vr pentagonal ; 

 in the latter case having its angles radially directed. Cirri, wlten present, interradial 

 in position. Sub-Carboniferous. 



Bdcmnocrinus, White. Burlington Group; Mississippi Valley. 



Family 5. Catillocrinidae. Wachsmutli and Springer. 



Base monocydic ; dorsal cup * m-rr- shaped ; general symmetry of the calyx 

 greatly disturbed. Basals irregular in form, their number unknown ; radials still 

 more irregular both in form and in size. Most of the arms given off from two of 

 the radials, n-lii<-h are sometimes five or six times larger than the other three; they 

 are simple, quadrangular, ami rest within small sockets directly upon the radials. 

 Anal plates wanting. Ventral tube heavy, composed of very long, longitudinally 

 arrange*/ crescent-shaped pieces, and supported directly by the radials; it exhibits a 

 wide open groove along the anterior side, which prolaUy -iw* covered by small 



- Devonian arid Sub-Carboniferous. 



< '"fillocrinus, Troost. Crown, when the arms are closed, elongate, cylindrical. 

 Calyx basin-shaped, concave at the base, truncate at its upper margin. Basal 

 disk small. R five ; those of the two antero-lateral rays fully six times as wide 

 as the others, and expanding upwards, so as to encroach upon the smaller ones. 

 The larger R support twelve to sixteen arms ; the smaller ones rarely more 

 than one each. Sub-Carboniferous ; North America. 



Mycocrinus, Schultze. Dorsal cup mushroom -shaped. Plates massive, 

 irregular, and without ornamentation. B two (according to Schultze), one of 



