81 l: oKDER C 



CONULARIDA 



H blunt median keel. Surface smooth or in'tli inn', transverse striae, rarely longitudinally 

 ^i i- i^t I'd or ribbed. Aperture coinylitihi <-l<>*> il I*,/ ,< operculum, the latter being semi- 

 i-finihtr, triangular, or lentifonn, >'//// lateral nucleus, and concentrically x//-/'<//r*/. 

 ( 'aiiiln-ian to Permian. 



The shells belonging here are of large size, and composed of calcium carbonate 

 The posterior portion is often divided off by 

 transverse septa. 



According to Holm, the typical genus Hyolithes, 

 Eichwald (Theca, Sowb. ; Pugiunculus, Barr), (Fig. 

 1024), is divisible into two sub-genera. One of 

 these, Orthotheca, Novak, contains forms with an 

 abruptly truncated anterior end ; and in the 

 other, Hyolithes, s. str., the margin of the flattened 

 side projects somewhat above the opposite wall. 

 The forms known as Cleidotheca, Centrotheca, 

 Salter ; Camerotheca, Diplotheca, Matthew ; Phare- 

 trella, Hall ; Ceratotheca and Bactrotheca, Novak, 

 fall within the synonomy of Hyolithes. This 

 genus is abundantly distributed in the Cambrian, 

 Ordovician, and Silurian of North America, Great 

 Britain, Sweden, Russia, 



and Bohemia ; it occurs (Etage' D)7 Lodenicer'BohemiaT Slightly' 

 ermrinrrlv ilan in tnP TV reduced. C, II. HKi.rinuix, Ha IT. Cambrian 

 Sparingly alSO in tlie L>e- (6tage C); ' MleschitZ) Bohemia. Anterior 



VOnian, Carboniferous, and portion restored, with operculum ; viewed 



-P. . from the side, 1/9. D, Operculum (after 



Permian. Barrande). 



Pterotheca, Salter; 



Phragmotheca, Barrande. Silurian. Matthewia, "Walcott. 

 Cambrian. 



Family 4. Conulariidae. Walcott. 



Shell rectilinear, inversely conical, rect- 

 angular to rhombic in cross -section, "///, 

 usually sharp edges, acute or truncated pos- 

 teriorly. Each of the transversely striated or 

 ribbed lateral faces divided into longitudinal 

 halves by a superficial groove, corresponding 

 internally to a median ridge. Posterior 

 portion of the shell divided off by septa. 

 Aperture constricted by four triangular or 

 linguiform incurved lobes of the anterior 

 margin. Ordovician to Jura. 



I 'I... 1026. 



Conularia quail i-ixul- 

 cata, Sowb. Upper 

 Carboniferous I. me- 



FIG. 1025. 



Conularia anomala, Barr. 

 Ordovician (EtageD); 

 Drabov, Bohemia. 



Gonularia, Mill. (Figs. 1025, 1026). 

 : This, the solitary genus, sometimes attains 



i a length of 20 cm., and is represented bv 

 &rgine (after Ethe- , ' . J ,. ., 



ridge). about 100 species. Its maximum distribu- 



tion occurs in the Ordovician and Silurian 



of Bohemia, Normandy, England, Sweden, and North America, and in the Devonian 

 of North America and Bolivia. It is rare in the Carboniferous and Permian, and 

 the last surviving species occurs in the Trias and Lias. 



