30 THE STORY OF ANIMAL LIFE 



Order ZYGOBRANCHIATA, AZYGOBRANCHIATA, 



or Streptoneura or Streptoneura, 



with a pair of with only one 



gills. gill. 



Genus Patella, the Lim- Littorina, the Peri- 

 pet, with gills winkle, or Shore 

 obliterated, and Shell, 

 only indirectly 

 represented; 

 breathing is per- 

 formed by folds 

 of the mantle. 



Species Vulgata, the Com- Littoralis, the (Yel- 



mon Limpet. low) Periwinkle 

 that lives above 

 low-tide-mark. 



CHAPTER III 



CLASSIFICATION, OR THE SORTING OF THE 

 ANIMAL KINGDOM 



GIVE a child a few handfuls of shells. Prob- 

 ably the first thing he will do with them is to sort 

 out the various kinds and separate them from one 

 another. Each will go into a little heap by itself; 

 and next, our young friend will find names for 

 them. These are Cap-shells and those Sword- 

 shells; these Saucers and those Plates; these 

 Yellow-shells and those Pink-shells according as 

 some special character or form or colour strikes 

 his fancy. 



Now this is what zoologists have been doing 



