20 The Developmental Characters of 



species, we thus arrive at a more certain indication of the 

 true affinities, i. e., the blood relationships, than by com- 

 paring adult individuals only. 



In order to show the application of these principles, I may 

 perhaps be permitted to give a hypothetical case. Suppose, 

 for example, that the foals of the horse were frequently or 

 invariably striped when yomig, but lost then' stripes as they 

 grew towards maturit3\ We should be justified on this 

 ground alone in believing, with a great amount of proba- 

 bility, that the horse had descended from a striped ancestor, 

 and if the foals of an allied species, such as the ass, were 

 also striped when young, this probability would be greatly 

 increased. If, on extending our comparisons, we found that 

 other allied species, such as the zebra, were striped through- 

 out their lives, we should conclude, in accordance with the 

 principles of the descent theory, that the horse and ass were 

 derived with the zebra from a common ancestor having the 

 characters of the latter species, and since the horse and ass 

 have, so to speak, outgrown the striped stage of their 

 existence, which, on our supposition, is retained only during 

 a short period of their j^ounger stages of growth, we should 

 say that these species were further advanced in development 

 i. e., were phyleticalUj yuunyer than the zebra. 



From the above considerations, it will be seen that the 

 ontogenetic development may thus throw much light on the 

 past historj' of a species or group, and through this on the 

 true systematic affinities. I may now pass on to our imme- 

 diate subject. 



The two systems of classification now made use of by our 

 Lepidopterists are those adopted in Stainton's * Manual of 

 Butterflies and Moths ' (1857), and by Doubleday in his 

 ' Synonj^mic List ' (1866). In the former, the Noctuina are 

 X^laced between the Bombycina and the Geometrina ; in the 

 latter, the Geometrse follow the Nocturni (Sphinges and 

 Bombyces of Linn^us), and are in then- turn followed by the 

 Noctuae, with which they are connected by the Drepanulae 

 and Pseudo-Bombyces. It is here quite unnecessary to 

 enter into the histories of these two systems of classification. 



