ARGIOPE. 19 



that lias hitherto been discovered for the present spe- 

 cies ; nor has it been noticed as inhabiting the northern 

 or western coasts of France. Its sonthern range extends 

 from the Mediterranean to the iEgean, as well as to 

 Madeira and the Canaries, at depths varying from 20 to 

 60 fathoms. 



The upper valve of this curious shell is like a horse's 

 hoof. The plates or ribs of the skeleton are not con- 

 tinuous, but separately attached to the sides of the 

 septa. 



Gmelin changed the original name to detruncata, 

 without assigning any reason, and he even recognized 

 the priority of Chemnitz by a correct reference to his 

 work. According to Philippi, it is the Terebratula 

 aperta of Blainville, and perhaps the T. urna antiqua and 

 T. cardlta of Risso. I should be inclined to consider 

 also the T. Soldaniana of the last-named author as the 

 young of the present species. 



B. Shell smooth. 

 2. A. cistel'ltjla *, SearlesWood. 



Terebratula cisteUula, S. Wood in Ann. N. H. vi. p. 253. Mcgathyris 

 (afterwards changed to Argiope) cistelhda, F.&H. ii. p. 361, pl.lvii. f.9. 



Body yellowish-brown : mantle so extremely thin as to be 

 scarcely visible : arms heart-shaped ; cirri few and thick : 

 peduncle rather long. 



Shell oval, heart-shaped, or oblong, and often wedge-like, 

 compressed but rising gradually towards the beak, rather solid, 

 occasionally somewhat glossy, but more frequently of a dull 

 aspect, sometimes bilobed or cleft in the middle : sculpture, 

 lines of growth numerous and exceedingly minute ; tubercles 

 close -set, and not very small : colotir brown, with usually a 

 yellowish tint : margins rounded at the sides and also slightly 

 in front, forming behind angles of different degrees: beak 



* A little chest. 



