GLASS ll 



CYSTOIDEA 



183 



radiating from the mouth towards the arm bases. Ordovician (Vaginaten- 

 kalk) ; Russia, Sweden, and England. S. pomum, Gyll. 



Glyptosphaerites, Mull. (Fig. 299). Differs from the preceding in having 

 long, branching, ambulacral grooves, and a short, well - developed stem.. 

 Ordovician ; Russia and Sweden. 



Protocrinites, Eichw. (Fig. 300). Nearly hemispherical, non-pedunculate. 

 Ambulacra grooves long and branching ; arms unknown. Ordovician ; Russia. 



Fungocystites, Barrande. Clavate. Ordovician (Etage D) ; Bohemia. 



Proteocystites, Barrande. Devonian (Etage F) ; Bohemia. 



Holocystites, Hall (Megacystites, Hall). Elongated, cylindrical, or sub- 

 cylindrical ; short -stemmed or stemless ; with subcentral mouth. Arms 

 minute, springing from the ends of the ambulacral grooves. Silurian ; North 

 America, Gottland. 



Eucystis, Angelin. Ordovician. Gomphocystis, Hall. Silurian. 



Family 3. Camarocystidae. Barrande. 



Calyx globose or discoid, composed of numerous polygonal plates, and sometimes 

 fixed by tlie ventral surface. Interior of calyx divided into four to six compartments 

 fit/ /HI rfif ions corresponding in position to lobes on the exterior. Stem long and slender. 

 Silurian. 



This family embraces two genera whose systematic position is still doubt- 

 ful. The larger, Camarocrinus, Hall ( = Lobolithes, Barrande), occurs in the 

 middle and upper members of the Silurian in North America and Bohemia, 

 and attains considerable size. The smaller, Lichenocrinus, Hall, is more or less 

 crateriform, has a very long, tapering stem, and is invariably attached by its 

 flattened ventral surface. It is found in the Ordovician (Hudson River 

 Group) of North America. 



Family 4. Echinosphaeritidae. Neumayr. 



Calyx globular or bursiform, adherent or with short stem, and composed of 

 numerous, irregularly arranged plates, all of which are furnished with pore-rhombs. 



FIG. 301. 



l-j-h ! nnsphaerites aurantium, Hising. sp. Ordovician (Vaginatenkalk) ; Pulkowa, Russia, a, Summit view of 

 c.-ilyx ; >i. Calyx swn from the anal side; c, Mouth, arms, and covered ambulacral grooves; d, Calyx plates 

 enlarged, showing pore-rhombs (cf. Fig. 296). 



Ambulacral grooves short ; arms two to five, free, Userial, rarely preserved. Stem, 

 when present, composed of several vertical series of alternately arranged plates. 

 Ordovician and Silurian. 



Echinosphaerites, Wahlenb. (Fig. 301). Globose, non-pedunculate. Mouth 

 central, ambulacral grooves short. Anal opening protected by valvular 



