BEACHIOPODA. 



885 



edges rolled together and uiiited, forming a large permanently- 

 open tube for the brachial ciirrents. The large spines are most 

 usually situated on the ears of the ventral valve, and may have 

 served to moor the shell ; being tubular they were permanently- 

 susceptible of growth and repair. Although edentulous, the 

 dorsal valve must have turned on its long hinge-line with as 

 much precision as in those genera which are regularly articulated 

 by teeth. 



Fossil, 81 species. Devonian — Permian. North and South 

 America, Europe, Spitzbergen, Thibet, Australia. 



Exterior. 



Fig. 190. 



Interior. 



Suh-genus. Aulosteges,'^Q\m.QTSQn. A. Wangenheimii, Vern., 

 Pig. 190. Permian, Eusssia; Oarb. Shell like Producta; 

 ventral valve with a large flat triangular hinge-area {h), with a 

 narrow convex pseudo-deltidium {d) in the centre ; beak a little 

 distorted, as if attached when young ; dorsal valve slightly- 

 convex near the umbo ; interior as in Productus (longi-spinus). 



Strophalosia, King. 



Examjole, S. Cancrini, De Yern., Pig. 

 191. 



Synonym, Orthothrix, Geinitz. 



Skell attached by the umbo of the 

 ventral valve ; sub -quadrate ; covered 

 with long slender spines ; valves arti- 

 culated, dorsal moderately concave, 

 ventral convex, each with a small area ; 

 fissure covered; vascular impressions 

 conjoined, reniform. 



Fossil, 8 species. Devonian — Carb. 

 Europe, Himalaya (Gerard). 



Fig. 191. )S. Cancrini. 



