354 MANUAL OF TTTE MOLLUSCA. 



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

 ■with ciliated bands. (Miiller.) 



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



Suh-genus ? Spo7igiobranchcea, D'Orbigny. S. Australia, PI. 

 XIV., Fig. 46. Gill (?) forming a spongy ring at the end 

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

 bution, 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 Gaimard. 



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

 Les.). 



Tijpe, P. alba, PI. XIV., Fig. 49. Amboyna. 



Animal fusiform, truncated in front, rough; neck slightly 

 contracted ; fins small, fan-shaped. 



Cymodocea, D'Orbigny, 



Etymology, Kumodoke, a Nereid. 



Type, C. 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 probosci- 

 diform. 



Distribution, 1 species. Atlantic. 



CHAPTER III. 



CLASS IV.— BEACHIOPODA, Cuvier, 1805. 



(= Order Pallio-branchiata, Blainville, Prodr. 1814.) 



The Bracliiopoda are bivalve shell-fish which diff'er 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 (Meuschen, 

 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 structui-e of each genus is illustrated in the woodoitta, which axe 



