ARGIOPE. 19 



that has hitherto been discovered for the present spe- 

 cies ; nor has it been noticed as inhabiting the northern 

 or western coasts of France. Its southern range extends 

 from the Mediterranean to the ^Egean, 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. cardita 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. 



f*\Kjo^tt^y>tj CtJfeAoJtf- 



. Y ** 2. A. CISTEL'LTTLA */ Searles Wood) H' X 9 



Terebratula cistellula, S. Wood in Ann. N. H. vi. p. 253. Megathyris 

 (afterwards changed to Argiope} cistellula, F. & H. ii. p. 361, pi. Ivii. 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 : colour 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. 



