CLASS II 



BEACHIOPODA 



411 



Hall and Clarke. Essentially Devonian but persisting into Carboniferous ; 

 distribution general. 



Subgenus Syringothyris Winchell {Syringopleura Schuchert). Like Adolfia, 

 but usually with large and erect ventral cardinal areas, and always with an 

 internal tube or syrinx, situated in the delthyriura. Upper Devonian and 

 Lower Carboniferous ; widely distributed. 



A D 



Fio. 622. 



A, Spirifer striatus (Martin). Lower Carboniferous ; Ireland. Portion of dorsal valve removed, showing 

 spiralia, •V4 (aifter Davidson). B, S. (Adolfia?) speciosus (Scliloth.). Devonian; Eifel. i/j. C, S. (Adolfia?) 

 macropterus (Goldf.). Devonian ; Coblenz. Mould, i/j. D, S. (Choristites) mosquensis Vern. Middle Carboni- 

 ferous ; Moscow. E, Same, interior of ventral valve, i/j. p, Pseudodeltidium ; x, Dental plates. 



Subgenus Syringospira Kindle. Like Syringothyris, but with a striate fold 

 and sinus. Upper Devonian ; New Mexico. 



Subgenus Delthyris Dalman. Small early Spirifers that are coarsely plicate 

 except on the fold and sinus. Surface lamellose ; the imbricating lamellae 

 marked with very fine radiating striae which do not terminate in spines. 

 Short dental lamellae present along with a more or less high ventral median 

 septum. Resemble Spiriferhia, but the shell structure is not finely and 

 regularly punctate. Genotype D. elevata Dalman. Section Lamellosi-Septati 

 Hall and Clarke. Silurian and Devonian ; distribution general. 



Subgenus Eospirifer, novum. Quadrate or alate early Spirifers that are 

 either smooth, radially undulate, or plicate, but without plications on fold and 

 sinus. Surface with additional fine, filiform, radiating striae which may be 

 minutely crenulate or granulose. Dental lamellae present. Genotype Spirifer 

 radiatus Sowerby. Section Eadiati Hall and Clarke. Essentially Silurian 

 but persisting into Lower Devonian ; distribution general. 



