302 THE I1S 7 DUCTIONS OF BIOLOGY. 



tions existing among the several great groups of the animal 

 kingdom, by placing these groups at the ends of four or five 

 radii, diverging from a centre. The diagram I cannot 

 obtain; but in the published reports of his lectures at the 

 School of Mines the groups were arranged thus : 



VERTEBRATA 



(Abranchiata) 

 Mammalia 



Reptilia 



(Branchiata) 



Amphibia 



Pisces 



MOLLTTSOA ANNULOSA 



Cephalopoda Heteropoda ) Articulata 



Gasteropoda- > Insecta Arachnida 



dioecia ) Myriapoda Crustacea 



( Pulmonata Gasteropoda- 

 \ Pteropoda monoacia Annuloida 



Lamellibranchiata Annellata Scoleidae 



Echinodermata Trematoda 

 Rotifera Tceniadae 



Turbellaria 

 Nematoideu 



CffiLENTERATA 

 Hydrozoa Actinozoa. 



PROTOZOA 

 Infusoria Spongiadaa Gregarinidae 



Foraminifera Thallassicollida 



"What remnant there may seem to be of linear succession 

 in some of these sub-groups, is merely an accident of typo- 

 graphical convenience. Each of them is to be regarded 

 simply as a cluster. Were Prof. Huxley now to revise this 

 scheme, he would probably separate more completely some of 

 the great sub-groups, in conformity with the views expressed 

 in his Hunterian Lectures delivered at the College of Sur- 

 geons in 1863. And if he were further to develop the 

 arrangement, by dispersing the sub-groups and sub-sub- 

 groups on the same principle, there would result an arrange- 



