174 MYADiE. 



the shell and in the principal features of the animal. Their 

 external ligament, and the absence of the spoon-shaped 

 process of hiuge, distinguish the former : the peculiar struc- 

 ture of the mantle and foot are characteristic of the latter. 

 The animal of this genus was not known to Menard, and 

 remained undescrihed until 1839, when a valuable mono- 

 graph on Panopeea was published by Valenciennes in the 

 first volume of the "Archives du Museum." In that me- 

 moir an account was given of the animal of Fanopcea 

 australist a south African species. The officers of a French 

 frisrate visitingf Port Natal observed the tubes of a Mollusk 

 projecting from the sand in one of the bays. The sailors 

 endeavoured to draw the creature out of its habitation by 

 the tube, but in vain ; for the siphons, after offering consi- 

 derable resistance, in every instance gave way, and often 

 were withdrawn entire in spite of the grasp of its persecu- 

 tor. Curious to know the nature of the being which thus 

 escaped them, they dug for it with spades, and at length 

 uncovered the Panopecfc buried several feet below the sur- 

 face of the sand, and gregarious. 



This genus was anciently of more importance than now, 

 for during the Jurassic epoch there existed many species in 

 our seas. They gradually decreased in numbers till the 

 present time. The few species known now are natives 

 of the North Atlantic, Lusitanian, South African, Pata- 

 gonian, and New Zealand seas, one only inhabiting each 

 region. 



P. NoRVEGicA, Spengler. 



Plate XI. (slightly enlarged). 



Mya Norvcgiai, Spengler, Skrivt. Naturli. Selskab. vol. iii. part 1, p. 4C, pi. 2, 



f. liJ. 

 (Hyduieris arduxi, Lam. Anim. s. Vert. (Uesh. cd. 2) vol. vi. p. 70. 



