210 ON SYSTEMATIC ZOOLOGY. 



sporting, as it were, with every thing hke regularity. 

 But this, I apprehend, is the consequence of a too rapid 

 glance ; since nature, so far from forgetting order, has, 

 at the commencement of her work, in these imperfect 

 animals, given us a sketch of the five different forms 

 which she intended afterwards to adopt for the whole 

 animal kingdom. In the soft, mucous, sluggish Intes- 

 tina, she has given the outline of the Mollusca. In the 

 fleshy living mass which surrounds the tony and hollow 

 axis of the Polypi natantes, she has sketched a verte- 

 brated animal. In the crustaceous covering of the 

 living mass, and the structure, more or less articulated, 

 of the Polypi vaginati, we trace the form of the Annu- 

 losa J while the radiated forms of the Rotifera, and the 

 simple structure of the Polypi rudes, may, in general, 

 remind us of the Radiata." * Assuming, therefore, that 

 the Acrita, as here defined, is really a natural group, 

 and allowing the analogies for the sake of explaining 

 the principle, we see a complete exemplification of our 

 author's meaning in one of the primary groups of the 

 animal kingdom. We shall now cite another instance 

 given by him in one of the smallest groups, namely, 

 the typical group of the genus Scarahceusi^Gymnopleiirus, 

 111.). In speaking of this, our author thus expresses 

 himself: — '" I have thus attempted to find characters 

 for the natural groups which appear on disposing the 

 Gymnopleuri according to their affinities ; but the proper 

 method of considering them all is, as referable to one 

 or other of forms which may be expressed by the five 

 following species: — 1. Asureus ; 2. Flagellatus ; 3. 

 Ccerulescens ; 4. Kcenigii ; 5. Miliaris. In almost 

 every group which has been set before the reader, he 

 must have perceived that one of the five minor groups, 

 into which it is resolvable, bears a resemblance to all the 

 rest ; or, more strictly speaking, consists of types which 

 represent those of each of the four other groups, toge- 

 ther with a type pecuhar to itself. This is visible in 

 the composition of the Acrita among the divisions of the 



^ * Hor. Ent 223. 



