2 SO ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



case, we are bound to make the smallest amount of assump- 

 tion by assigning to the various groups of organisms the 

 places which they will fit into, on the supposition that they 

 do represent in reality the original progressive series. . . . 

 When, therefore, the hypothesis of degeneration presents it- 

 self as a solution of any special morphological difficulty, we 

 need have no scruples or prejudices in favor of the doctrine 

 of universal progression which should prevent us from ac- 

 cepting it." Thus reasoning, he urges that the Tunicates 

 are degraded Vertebrates; that their systematic relations 

 with the members of that group are evidenced by the chorda 

 of the larval stage ; and that there has been quite a general 

 tendency towards degeneration in these animals. 



Professor Lankester has further expressed his views of the 

 classification of the Vertebrates, as well as other types of 

 the animal kingdom, in the following condensed arrange- 



ZD J CD CD 



ment : 



Branch A. Ueochoeda. 



(1.) I. Larvalia ("Tunicates" of genera Appendicularia 



and Kowalewskyict). 

 (2.) II. Saccata (" Tunicates " of typical form). 



Beancii B. Cephalochorda [=Leptocardia, Haeckel]. 

 (3.) I. Leptocardia [=Acrania } Haeckel]. 



Beancii C. Ceaniata [=Pachycardia, Haeckel]. 

 Grade A. Cyclostoma (Monorrhina [Haeckel]). 



(4.) I. Hyperotreta. 

 (5.) II. Hyperoartia. 



Grade B. Gnathostoma (Amphirrhina [Haeckel]). 



Sub-grade A. Heterodactyla branchiata [ = Lyrifera, Gill]. 



(G.) I. Pisces (with sub-classes Selachii, Holocephali, Ga- 



noida?, Teleostei). 

 (7.) II. Dipnoi. 



Sub-grade B. Pentadactyla branchiata \\ = Batrachopsidn, 



Gill]. 



(8.) I. Amphibia (with sub-classes Lissamphibia [=^Un> 



