34 CLASSIFICATION 



The nerves which go out of the skull are nine pairs, and the acces- 

 sorius, which goes out with the eighth. 



Classes of Animals according to their modes of Generation. 



1. Vivipara; those that bring forth [living young, formed] in the 

 uterus, from a mixture of male and female influence : such are all of the 

 first class [according to the structure of heart and lungs], both sea and 

 land. 



2. Vivum ex ovo \ovovivipara~] ; those that may be said to hatch their 

 young from an egg in the oviduct ; as, e. g., most vipers, slow-worms, 

 some lizards, salamanders : and this is confined to part of the second 

 class of hearts [Tricoilia] and to some of the third \_Dicoilia~], as in the 

 [piked] dog-fish. 



3. Ovi/para ; those that throw their eggs out and are hatched out of 

 the body. This takes in a large field, viz. part of the first class [Tetra- 

 coilia, i. e. Birds] and of the second class [Tricoilia], the greatest part 

 of the third [Dicoilia], and -perhaps all of the fourth [i. e. those with 

 lungs in their sides]. 



4. The mode of producing a continuation of the species in animals 

 may first be divided into two kinds : the one [by products of organs of 

 generation, as above defined] ; the other, which is the most simple, is 

 a part of any one animal becoming a whole, and, what is somewhat 

 similar, producing an animal out of itself — like a branch of a tree or 

 a sucker from a root : these [fissiparous and gemmiparous modes] admit 

 of considerable variety. 



There are three classes of animals which may be called oviparous l ; 

 the Bird, the Amphibia, and the tribe of Bay-fish. 



The Bird and the Amphibia are nearer each other in their operations : 

 but in some circumstances the Bay-fish is the same as the Amphibia, 

 in others very different. They are different, e.g., in the construction 

 of their eggs : they are somewhat different in their mode of receiving 

 the yolk into the abdomen. 



Classes of Animals according to the Coitus. 



In the first class they are male and female, and they insert 2 . In 

 the second they are male and female, but do not all insert ; some only 



1 [Here the word is restricted in its application to the animals which exclude 

 comparatively few and large eggs, and those successively, in contrast with the nume- 

 rous and simultaneously discharged small eggs of frogs and roe-fish.] 



2 [This applies to the Mammalia.'] 



