CHAPTER III. 



VARIOUS MOLLUSKS — THEIR STRUCTURE — WONDERS OF CREATIVE 

 POWER. 



The brachiopodous mollusks, so called from two 

 words, meaning an arm and a foot, consist of only a 

 limited number of beings ; they are comparatively sin- 

 gular in conformation, but at present imperfectly under- 

 stood. Like bivalve, or two-shelled mollusks, they are 

 inclosed in a shell consisting of two parts, covering a 

 double mantle, or two delicate semi-transparent mem- 

 branes, from which their dwellings are secreted. Two 

 of the genera, namely, lingula and terehratula, have a 

 tubular fleshy footstalk, or peduncle, by which, as in the 

 instance of the barnacle, they are permanently attached 

 to various bodies in the water ; but the genus or group 

 termed orhicida, is fixed to the rock, not by a peduncle, 

 but by the lower valve of the shell. 



Cuvier applied the term brachiopoda to these animals, 

 in allusion to two fleshy-fringed arms which they possess, 

 one on each side of the mouth : and which in most can 



