264 zooiiOGv. 



irregularly toothed : ***.<dfpejr recurved, pointed: **** 

 Entire, notpoiuted at the Apex : **'^**^4pex perforated. 



Limpets abound on rocky coasts, and may be found in 

 great abundance, adhering to rocks and stones ; the fresh 

 water species attach themselves to aquatic plants, they all 

 affix themselves so tenaceously, that it is with difficulty they 

 are remoied without injury. 



33, Dentalium. Tooth-Shell. Inhabitant a Terrebella, 



Shell nearly strait, slender, tubular, mostly pervious. Plate 

 5, fig. 33. 



These shells are all marine, they may be found on sandy 

 beaches at low water, generally in a perpendicular or oblique 

 direction, beneath the sand or mud, and are discoverable by 

 a slight depression ou the surface. 



34. Serpula. Worm-Shell. Inhabitant a Terrebella. 



Shell slender, tubular, usually adheriiig to other substances, 

 often divided iiiternaliy by imperforate partitions, at 

 irregular distances. Plate 5, ug. 34, .There are two 

 families in the genus : * Flexuous, irregular in shape, 

 and adhering fo other SiibsJances : ** assuming a de- 

 termined form, and detached. 



Like the last genus, these are conflued to the ocean, and 

 are often found in consid«jrable numbers, attached to other 

 shells, stones, and plants. 



