280 CRITIQUES AND ADDRESSES. [xi. 



Protista and Plants impossible. But if they are, who is 

 to define the Fungi from the Alga ? Yet the seaweeds 

 are surely, in every respect, plants. On the other hand, 

 Professor Haeckel puts the sponges among the Ccelente- 

 rata (or polypes and corals), with the double inconve- 

 nience, as it appears to me, of separating the sponges 

 from their immediate kindred, the Protoplasta, and de- 

 stroying the definition of the Ccdenterata. So again, 

 the Infusoria possess all the characters of animality, 

 but it can hardly be said that they are as clearly allied 

 to the worms as they are to the Noctilucce. 



On the whole, it appears to me to be most conve- 

 nient to adhere to the old plan of calling such of these 

 low forms as are more animal in habit, Protozoa, and 

 such as are more vegetal, Protophyta. 



Another considerable innovation is the proposition 

 to divide the class Pisces into the four groups of Lep- 

 tocardia, Cyclostomata, Pisces, and Dipneusta. As 

 regards the establishment of a separate class for the 

 Lancelet (Amphioxus), I think there can be little doubt 

 of the propriety of so doing, inasmuch as it is far more 

 different from all other fishes than they are from one 

 another. And there is much to be said in favour of 

 the same promotion of the Cyclostomata, or Lampreys 

 and Hags. But considering the close relation of the 

 Mudfish with the Ganoidei, and the wide differences 

 between the Elasmobranchii and the Teleostei, I 

 greatly doubt the propriety of separating the. Dip- 

 neusta, as a class, from the other Pisces. 



Professor Haeckel proposes to break up the vertebrate 

 sub-kingdom, first, into the two provinces of Leptocardia 

 and Pacliycardia ; Amphioxus being in the former, 

 and all other vertebrates in the latter division. The 

 Pacliycardia are then divided into Monorhina, which 

 contains the Cyclostome fishes, distinguished by their 



