112 
BBACHIOPODA. 
ARGIOPE 
Shell transversely oblong, or semicireular, 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 
rudimentary ; 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 fonn 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. 1847. 
Argiope (decollata), Desl. 1842, Mi™. Soc. Lin. Normand. viii. 
Dav. 1852, Ann. Nat. Hist. p. 372. 
Megathyris (decollata), Z)’Or5. 1848, Ann. Sc. Nat. 
Forbes Sf Hanley, Brit. Moll. 
Orthis, sp., Philippi, Moll. Sicil. 
Hagenow, Neues Jahrb. 
Terebratula, sp., Lamarck. 
Argiopidse, 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, Esq. The oral aperture is seen in the centre of the 
fringed brachial disk. 
