CHARACTERS OF THE RASORIAL FORM. 257 



creation. In no one instance do we find that suctorial 

 types, like the natatorial, are fixed, as are the Polypes 

 and the barnacles, to one particular spot : free powers of 

 locomotion, and these generally accompanied with great 

 agility, are, consequently, among its chief characters. 

 Nearly all the animals which, from imbibing their nour- 

 ishment by sucking the juices of others, and whose struc- 

 ture at the same time is very simple, are of this type : it 

 might, from this fact, be termed parasitic, for it comprises 

 almost every animal which usually bears that name. The 

 intestinal worms, the common Cimeac, Pediculus } a.nd Pu- 

 lex, the gold wasps (Chrysis], the Acari, or harvest bugs, 

 and the Cocci, or cochineal insects, are a few out of the 

 multitude of examples which can be proved, by analysis, 

 to be modifications of this primary type. Among qua- 

 drupeds, this latter character is not strongly developed ; 

 but every one knows the parasitic nature of the cuckow, 

 and the cow-pen bunting of America (Molothrus pecoris 

 Sw.); while the Gastrobranchus, among fishes, illustrates 

 this peculiarity in the most striking manner. 



(317-) The RASORIAL type, so termed in ornithology, 

 is the third and last which enters into the aberrant cir- 

 cle which circle is always closed by the union of this 

 type with the NATATORIAL ; hence it follows, that both 

 approximate in their general characters. First, as to 

 the form and structure of rasorial types. They are, in 

 general, remarkable for their size ; being inferior only to 

 the natatorial. From these they are further to be dis- 

 tinguished by the strength and perfection of their feet ; 

 the toes of which, in vertebrated animals, are never 

 united so as to be used for swimming. This perfection, 

 however, is of a very peculiar kind ; since it is confined 

 to the powers of walking on dry land, or of climbing 

 among trees. These scansorial powers, in fact, although 

 occasionally found in other types, are so very frequent 

 and remarkable in this, that it may be considered one 

 of the peculiarities of the rasorial structure. This is the 

 type so remarkable for the greatest developement of 

 tail ; and of those appendages, for ornament or defence, 



