112 



BRACHIOPODA. 



ARGIOPE. 



Shell transversely oblong, or semicircular, smooth, or orna- 

 mented with corresponding ribs, strongly punctate ; hinge-line 

 wide ; margins even ; dorsal valve depressed ; ventral valve trun- 

 cated at the beak ; area flat ; foramen large, rounded ; deltidium 

 nulimentary ; interior of dorsal valve furnished with one or more 

 prominent, submarginal septa (fig. 21-23) ; loop originating at 

 the base of the dental sockets, and folded into two or more lobes 

 occupying the interspaces of the radiating septa, to which they 

 adhere on their inner sides. 



Animal with oral arms united by membrane, forming a disk, 

 and folded so as to form two or four lobes ; mantle extending 

 to the margin of the valve and closely adherent (fig. 21). 



Terebratula, § F. (& D. part.), Blainv. D. S. N. liii. 145, 1828. 



Gray, P. Z. Soc. 184/. 

 Argiope (decollata), Desl. 1842, Mem. Soc. hin. Normand. viii. 



Dav. 1852, Ann. Nat. Hist. p. 3/2. 

 Megathyris (decollata), D'Orb. 1848, Ann. Sc. Nat. 



Forbes ^ Hanley, Brit. Moll. 

 Orthis, sp., Philippi, Moll. Sicil. 



Hagenoiv, Neues Jahrb. 

 Terebratula, sp., Lamarck. 

 Ai'giopidae, King, Permian Foss. 81. 142. 



Fig. 21. Argiope decollata. 



Fig. 21. — Dorsal valve with the animal, highly magnified, from a specimen in the 

 cabinet of Thomas Davidson, Ksq. The oral aperture is seen in the centre of the 

 fringed brachial disk. 



