BRACHIOPODA. 



335 



obtuse appendage near the base, and two processes closely- 

 locking into those of the lower valve. Animal unknown. 

 — 1 species. 



Found in the Mediterranean, and the species is called 

 Mediterranea in consequence. The interior of the upper 

 valve is curiously indented so as to fit certain parts of the 

 body of the animal ; these marks spread from the hinge, 

 and look exactly as if they were picked out in wax. The 

 inside of both valves is a pale green colour, and finely 

 granulated. 



Order II. 



HELICTOPODA. 



The mouth arms of the animal are, when in repose, 

 regular, and spirally rolled together ; the mantle lobes are 

 placed close to the interior surface of the valves (but the 

 valves are not pierced with minute perforations like those 

 of Terebratulidae) ; the shell has sometimes small pointed 

 appendages on the exterior, which during the increase of 

 the shell were formed at the edge. 



Family 1. — S PI RIFE RID JE. 



The mouth arms are very strongly developed, and are 

 supported in their whole length by a thin calcareous, or 

 cartilaginous ? spirally twisted plate. Only known in the 

 fossil state. 



Spirifer. Sow. (Delthyris Dalman ; Choristites 

 Fischer; Trigonotreta Konig ; Brachythyris M'Coy.) — 



