620 TAXONOMY. 



These circles, which the Mandibulala and Hauslellata form, are 

 contiguous to each other in the Trichoptera and Lcpidoptera, espe- 

 cially the genus Mystacides, Latr., of the former, makes the transition 

 to the genus Aglussa, Latr., in the latter. M'Leay considered 

 the following families as the connecting links between the two 

 orders of 

 Mandibulata and Haustellata. 



Bomboptera. Genus Psychoda. 



( Tenthrenodea, stand between the (Between Lepidoptera and Dip- 

 Trichoplera and Hymenoptera. tera. 



Strcpsiptera, Kirb. Homaloptera. 



(Between Hymenoptera and Cole- (Diplera puplpara, Lat., between 



optera. Diptera and Aptera. 



Dermaptera, Leach. Genus Aphis. 



(Between Coleoptera and Orthop- (Between Aptera and Hemiptera. 



tera. 



Dictyoptera, Lea., Kirb. Family Hydrocorides, Latr. 



(Between Orthoptera and Neu- (Between Hemiptera and Hunio- 



tera. ptera. 



Megalopiera. Genus Aleyrodes,liair. 



(Semblodes between Neuroptera (Between Homoptera and Lepi- 



and Trichoptera. doptera. 



It is not to be denied that in this arrangement there are many 

 affinities, but just as many appear forced and unnatural. The opinion 

 that has also been expressed by Goldfuss and other German naturalists 

 appears indeed true, that animals in general, and consequently insects, 

 do not ascend in a consecutive series from the most simple to the most 

 perfect, but the several groups touch each other in different parts, 

 thereby receiving other forms, and are frequently interlinked by true 

 groups of transition. If, now, the determinate adoption of five chief 

 groups appears forced, and without a sufficient reason, if also we cannot 

 detect in what relation the osculant groups stand in the system of the 

 author to the chief ones, whether they are equivalent or subordinate, 

 and if, lastly, the Hemiptera are incorrectly divided into two orders, 

 and the entire order of the Trichoptera must be considered as artificial, 

 as the Phryganece, Scmblodes, and Tenlhredonodca are united, we 

 must yet admit that the author has exhibited considerable skill, correct 

 judgment and knowledge of the whole, and that his system as an essay 



