GASTEROPODA. 



the group : their shell is slightly spiral at its commencement, but rapidly ex- 

 pands, so as somewhat to resemble in its shape the human ear, whence the 

 origin of the name. The circumference of the foot and the sides of the head 

 of the living animal are decorated with elegant fringes, and the shell is like- 

 wise perforated with a row of apertures through which gorgeously-coloured 



filaments are protruded: these aper- 

 tures also serve for the free admis- 

 sion of water to the branchial cham- 

 ber. The mouth is a short proboscis. 

 The Key -hole Limpets (Fis- 

 snrella) very much resemble the 

 common limpets of our coast, and 

 in like manner are provided with 

 a plain conical shell, without any 

 spire, which spreads over the middle 

 FH;. M5.-F1SSUKBLI.A RETICULATA. of their back. They differ from the 



limpets, however, in having the 



shell perforated at its apex for the purpose of admitting the water into a 

 branchial chamber in which pectinated gills are lodged. 



ORDER TECTIBRANCHIATA.* 



The Gasteropods belonging to this Order have their branchiae 

 arranged along the right side of the body or on the back ; they are 



always in the form 

 of leaflets more or 

 less divided, but 

 not symmetrical : 

 theyare protected 

 by a sort of roof, 

 formed by a pro- 

 longation of the 

 mantle. These 

 animals are for the 

 most part naked 

 slugs ; but some 

 have a small shell 

 concealed in the 

 mantle, and others 

 We select as an 



226. SKA-HARE. 



have a conspicuous one of considerable size, 

 example of this order 



The Sea-Hares (Aplysid] frequently found in fishermen's nets. When 

 captured and put into a vessel of water, they have the power of discharging, 

 in great abundance, a fluid of a rich purple hue, which quickly diffuses its 



* Tectu?;, covered : branchice, gills: cover fil gills. 



