43 



Semiothisa californiata, no Phasiane orillata, no Thamnbnoma guenehia, if 

 would be easy to define these genera, and separate them by well-marked 

 characters ; but the lowest species combine more or less the characters of 

 the different genera, and the three groups seem to diverge from a form like 

 any one of the above-mentioned species. Such species are synthetic types, 

 combining the characters of the three genera to which they belong. It is 

 impossible to say which of the three genera is the higher. In fact, they are 

 somewhat parallel forms, like the topmost branches of a tree. It is so with 

 the genera. Thamnonoma and Evfitchia vary in different directions in one 

 or two or three characters, viz, in the venation, in the form of the abdomen, 

 in the peripheral characters, and especially coloration. The genus Eumacaria 

 is one of much interest, as, while closely allied to Se?niothisa in its structural 

 features, it anticipates Epione in its general appearance and markings, so that 

 it would be easily regarded as belonging to the Ennominte. 



It thus appears that there may be synthetic types among species and 

 genera. It also appears that there may be synthetic types between two fam- 

 ilies, such as Doryodes and Sudariophora and Ligia, which are Noctuids, with 

 some phalaenid characters. 



It is not improbable that these so-called synthetic or comprehensive 

 types are ancestral forms from which other species and genera have diverged. 



§ 1J. — Mimicry op natural objects. 



No cases of mimicry of other insects, so far as I 

 am aware, are known to occur among the larvre or 

 imagines of this family. That, however, the geometrid 

 caterpillars closely resemble the twigs of the plants on 

 which they rest was noticed by Linnaeus in the tenth 

 edition of his " System a Naturae." The most remark- 

 able example which has fallen under my observation is 

 the larva of Drepanodes varus, Gr. & R., which lives on ^3^, 

 the stems of the juniper-bush. The best description 

 that could be given of it is to say that it would easily 

 be mistaken, as it holds itself straight out motionless 

 by means of its anal legs, for a portion of a twig of the 

 tree on which it feeds. It is about an inch and a half 

 long, and less than a line in thickness. Its body is quite 



