336 



MOLLU SCOIDEA BRAOHIOPODA 



SUB-KINGDOM V 



The species of Spirifer have recently been grouped by Hall and Clarke into six 

 sections as follows : Radiati, with fine filiform striae ; Lamellosi, with concentric 



A, Spirifer striatus, Sow. Carboniferous Limestone ; Ireland. Portion of dorsal valve removed, showing 

 spiralia, a / 4 (after Davidson). B, S. speciosus, Schloth. sp. Devonian ; Eifel. 1/1- C, S. macropterus, Goldf. sp. 

 Devonian ; Coblenz. Cast, 1/1- D, S. Mosquensis, Vern. Sub-Carboniferous ; Moscow. E, Same, interior of 

 ventral valve, !/] (p, Pseudodeltidium ; x, Dental plates). 



lamellae ( = Delthyris, Dalman) ; Fimbriati, with concentric rows of fine spines ( = Reti- 

 cularia, M' Coy) ; Aperturati, with plications on fold and sinus ; Ostiolati, with the 

 median fold and sinus without plications ; Glabrati, with the surface smooth and 

 glabrous ( = Martinia, M'Coy ; Martiniopsis, Waagen ; and Mentzelia, Quenstedt). 



Cyrtia, Dalman (Fig. 577). Distinguished from Spirifer by having an 

 unusually high ventral area, with its delthyrium closed by a perforated 

 deltarium. Silurian to Devonian ; Europe and North 

 America. 



Syringotkgris, "Winchell. Spirifer-like shells, usually 

 with large and erect cardinal areas and an internal tube 

 or syrinx, situated in the delthyrium. Carboniferous ; 

 North America and Europe. 



Ambocoelia, Hall. Small, concave, or plano-convex, 



saurian ; Gottiand. 'Natural usua u y smooth Spirifer-like shells. Four well-defined 

 adductor scars near the anterior margin in the dorsal 

 shell. Devonian tc Carboniferous ; North America and Europe. 



Ferneuilia, Hall and Clarke. Small Spirifers, with a deep median sinus 

 and two pronounced divergent ridges on each valve. Devonian to Carboni- 

 ferous ; Europe. 



FIG. 577. 

 Cyrtia exporrecta, Dalm. 



