370 



ESSAY ON CLASSIFICATION. 



next step should now be to apply these standards also to 

 the minor divisions of the animal kingdom, down to the 

 genera and species, and to do this for every class singly, 

 with special reference to the works of monographers. 

 But this is such an herculean task, that it can only be 

 accomplished by the combined eiforts of all naturalists, 

 during many years to come. 



below the insects. The general clas- 

 sification of the branch of Mollusks 

 appears the least satisfactory in this 

 work, for while the Tunicata are con- 

 sidered as a distinct class, and the 

 Conchifera as another, including the 

 Brachiopods, the class of Mollusca 

 proper includes not only the Ptero- 

 poda and Gasteropoda, but also the 

 Cephalopoda. Evidently, the Cepha- 

 lopoda are brought here into too 

 close connexion with the Gasteropoda. 

 A fuller consideration of the fossil 



Cephalopoda would easily have satis- 

 fied the author that these animals 

 constitute for themselves an inde- 

 pendent class. 



Since the publication of the Ani- 

 mal Kingdom of Cuvier, Van der 

 Hoeven's Text-book is the only gene- 

 ral work on Zoology, in which the 

 class of fishes is presented in a manner 

 indicating a thorough acquaintance 

 with this class of animals. The treat- 

 ment of the other Classes of Verte- 

 brata is equally deserving of praise. 



THE END. 



