Mr. S. r. AVoodwaid on Panopaea Aldrovandi. 117 



inner gill. The dorsal margin of the outer lamina is expanded be- 

 yond the line of snspension, and is fixed. 



The gills of the opposite sides are united to each other behind tlie 

 body and to tlie branchial septum. 



The whole structure is closely like that of Mija arenaria, the 

 chief differences being the shortness of the palpi, and the inequality 

 of the gills. 



There are nine other reputed recent species of PanopcBa. 



1. P. ABBREViATA, A^al. ; discovercd by M. d'Orbigny on the 

 coast of Patagonia between the R. Negro and S. Bias. This sliell 

 appears to have been again met with by the U. S. Exploring Expe- 

 dition, under Commander "Wilkes, and is described by Dr. Gould as 

 P. antarctica. 



2. P. ZELANDiCA, Quoy ; of wlucli an odd valve only was picked 

 up on the beach. 



3. P. SOLAN DRi, Gray ; probably the same as the last. 



4. P. AUSTRALis, G. Sby. (Genera of Shells, pi. 40. f. 2), one of 

 G. Humphrey's shells from New South Wales ; of which there is a 

 series in the British Museum, from Tasmania. 



.5. P. AUSTRALIS, Val. (not Sowerby's). 



This species is as large as P. Aldrovandi, and very like it. Being 

 quite distinct from the P. oustralis of Sowerby, it is proposed to call 

 it P. natalensis. 



It was discovered in the sandy bays of Port Natal, by Capt. Cecile 

 and the officers of the French frigate ' Heroine,' who observed the 

 tubes of the shell-fish projecting through the sand at low water. 



" The sailors endeavoured to draw the creature out of its habita- 

 tion by the tube, but in vain ; for the siphons, after offering con- 

 siderable resistance, in every instance gave way, and often were with- 

 drawn entire, in spite of the gras}) of its persecutor. Curious to 

 know the nature of the being which thus escaped them, tliey dug for 

 it with spades, and at length uncovered the Vanopcpa buried several 

 feet below the surface of the sand, and gregarious*." 



G. Panop.ea jAi'ONicA, A. Adams, Zool. Proc. for 1849, p. 1/0. 

 pi. 6. f. 0. This species, of which the original and unique example 

 is in the Leyden ^luseum, is nuich like the fossil P. intermedia of 

 the London clay. 



7. Panop.ea GENEROSA, Gould ; Pugct Souud, Oregon. (U. S. 

 Expl. Exped.) 



8. Panop.ea norvegica, Spengler, is found throughout the 

 Arctic seas, from Behring's Straits to Newfoundland, the North Sea 

 and Russian Lajtland. 



I was so convinced of the affinity of this shell to the Saxicava, that 

 (in my Manual) I placed the latter genus next to Panopcea ; it now 

 appears that I should have left it in its former place with Gastro- 

 chtena and have removed the Panopcea norveijicn to it. The shell 

 differs from Panopcea in having the pallial line broken up or divided 



* Forbes, i. p. 174, from Valenciennes' Archives du Museum, t. i. 1839. 

 Ann.i^ Mag. N. Hist. Ser. 2. Vol.w'm. 27 



