418 MOLLUSCOIDEA phylum v 



Adinoconchus M'Coy. Athyrids with very wide, radially striate, concentric 

 lamellae. Carboniferous ; Europe. 



Cleiofhyridina Buckman (Cleiothyris King, non Phillips). Athyrids with con- 

 centric rows of flat spinules. Carboniferous and Permian ; distribution 

 general. 



Composita Bronn {Seminula Hall and Clarke, non M'Coy). Genotype Spirifer 

 amhiguus Sowerby. Smooth-shelled Athyrids. Dorsal hinge-plate very pro- 

 minent. Carboniferous ; distribution general. 



Comelicania Freeh. Large, decidedly alate Athyrids with angulated sinuses 

 in both valves. Alpine Upper Permian. 



Janiceps Freeh. Small, sharply triangular Athyrids with angulated sinuses 

 in both valves. Alpine Upper Permian. 



Spirigerella AVaagen. Permian ; South America and India. 



Amphitomella Bittner. Smooth - shelled 

 Athyrids with a double cardinal process and 

 median septa in each valve. Alpine Trias. 



Tetraetinella Bittner (Plicigera Bittner) 

 (Fig. 633). Athyrids with four correspond- 

 ing ribs on each valve. Alpine Trias. Sub- 

 genus : Stolzenhurgiella Bittner. Alpine Trias. 

 Pentadinella Bittner. Athyrids with five 



TdmHlnella trigondln (8c]^\ott\eim). ,. ., , , ^-^ 



Muscheikaik ; Recoaro, Italy. Vi- corrcsponduig nos On each valve. Occurs in 



the Alpine Trias. 

 Anomadindla Bittner. Athyrids with a number of angular alternating 

 ribs towards the anterior margins. Alpine Trias. 



PomatospireUa Bittner. Small smooth shells having the contour of Dayia 

 or Cydospira. Alpine Trias. 



Subfamily B. Diplospireltjnae Schucliert. 



Specialised Athyridae (out of the Athyrinae), with the jugal bifurcations very 

 long, lying between the volutions of the spiralia, and continuing toith these to their 

 outer ends. Sometimes there is an additional jugal process which articulates with the 

 ventral valve, or recurves and joins the jugum. Devonian to Triassic. 



Kayseria Davidson. Lenticular, plicated shells with a median plicated 

 sinus on both valves. Jugum with a ventral articulating process and the 

 bifurcations continued between the spiral ribbons to their outer ends. 

 Devonian ; Germany. 



Diplospirella Bittner. Athyrids with the jugal processes coextensive 

 with the principal spiral coils. Alpine Trias. 



Pexidella Bittner. Athyrids difiering from Diplospirella in that the 

 jugum is much reduced and situated^ in the umbonal region. Valves much 

 thickened in the apical region. Alpine Trias. 



Euradinella Bittner. Diplospirellids with short corresponding ribs. 

 Alj)ine Trias. Didymospira. Salomon. Alpine Trias. 



AnisadineUa Bittner. Diplospirellids with alternating ribs. The 

 secondary spiral coils give oft' a process which returns and joins the jugum. 

 Alpine Trias. 



