354 MAirUAL OP THE MOLLUSC A. 



In the fry of Pneumodermon th© end of the body is encircled 



"with ciliated bands. (Miiller.) 



Distribution, 4 species. Atlantic, India, Pacific Ocean. 



Suh-genus ? Spongiohranchoea, D'Orbigny. S. Australis, PI. 

 XIY., Fig. 46. Grill (?) forming a spongy ring at the end 

 of the body ; tentacles each with 6 rather large suckers. Distri- 

 hution, 2 species. South Atlantic (Fry of Pneumodermon ?). 

 Trichocyclus, Eschscholtz, T. Dumerilii, PI. XIV., Fig. 43. 

 Animal without acetabuliferous tentacles ? mouth probosidi- 

 form ; front of the head surrounded with a circle of cilia, and 

 two others round the body. 



? Pelagia, Quoy and Graimard. 



Etymology, Pelagus, the deep sea (not = Pelagia, Peron aijd 

 Les.). 



Type, P. alba, PI. XIY., Fig. 49. Amboyna. 



Animal fusiform, truncated in front, rough; neck slightly 

 contracted ; fins small, fan-shaped. 



Cymodocea, D'Orbigny. 



Etymology, Kumodoke, a Nereid. 



Type, 0. diaphana, PI. XIV., Fig. 50. 



Animal fusiform, truncated in front, pointed behind ; neck 

 slightly contracted ; fins 2 on each side, first pair large and 

 rounded, lower pair ligulate ; foot elongated ; mouth probosoi- 

 diform. 



Distrihution, 1 species. Atlantic. 



CHAPTER III. 



CLASS IV.— BEACHIOPODA, Cuvier, 1805. 

 (= Order PalUo-hrunchiata, Blainville, Prodr. 1814.) 



The Brachiopoda are bivalve shell-fish which difier from the 

 ordinary mussels, cockles, &c., in being always equal-sided, and 

 never quite equivalve. Their forms are symmetrical, and so 

 commonly resemble antique lamps, that they were called 

 lampades, or "lamp-shells," by the old naturalists (Meuscheu, 

 1787, Humphreys, 1797) ; the hole which in a lamp admits the 

 wick serves in the lamp-shell for the passage of the pedicle by 

 which it is attached to submarine objects.* 



* The principal modifications of external form presented by these shells are given in 

 Plate 15 ; the internal structure of each genxis is illustrated in the woodcuts, which are 



