244 



CHAPTER YIII. 



Class IV. LAIVIELLIBRANCHIATA. 



Suet creatures earth owus not, nor yet tlie heavens. 

 Where hu'ds fly swiftly, carolling their songs. 

 And insects hum, uprising from their haunts 

 In groves or meadows. 



AVeat think you of a class of mollusks, headless,, in many 

 instances incapable of motion, and often bhnd; living 

 buried in the sand or crevices of rocks, and occasionally 

 attacliing themselves to marine substances by silken fila- 

 ments, yet susceptible of happiness, and subserving im- 

 portant purposes in the economy of nature ? 



Such are the Lamellihrancliiata (from lamella, diminutive 

 of lamina J a thin plate, and IrancJiice, gills), the fourth class 

 into which the subkingdom MoUusca is divided, an exten- 

 sive tribe "whose mantle is formed into two lobes, each of 

 which produces a separate piece of shell, connected by a 



