114 Mr. P. A. Buxton on the 



Earwig and other types (see Bibliography), which giyes a 

 full review of insect neurology up to 1913, together with a 

 bibliography and a table of the terminology of the insect 

 brain, which has materially lightened my labours. This 

 paper is by far the most important contribution which has 

 yet been made to insect neurology. 



All my material has been collected in the neighbourhood 

 of Cambridge, and I haye worked entirely with Micro- 

 pteryx (Eriocephala) * caUhella (Linn.), and not with any 

 other species. 



INTRODUCTION. 



The anterior part of the central neryous system of insects 

 consists of a supraoesophageal portion, which is the brain in 

 the narrow sense of the word. From this the circum- 

 oesophageal commissures pass round the oesophagus to the 

 ventrocerebrum or suboesophageal portion of the brain. 

 Most authors include this also in the brain of the insect. 

 The supraoesophageal ganglion, or brain in the narrow sense 

 of the word, was found by Viallanes to be composed of three 

 paired elements or neuromeres, which he belie yed to be 

 segmental ; these giye rise to the parts of the brain to which 

 he gaye the names Protocerebrum, Deuterocerebrum (or 

 Deutocerebrum) and Tritocerebrum. We now know that 

 the Protocerebrum is not a segmental ganglion ; and it 

 will be conyenient at this point to giye a short summary of 

 the results obtained by those who haye studied the subject 

 of the segmentation of the head of the Arthropoda, and the 

 homologies of the various appendages throughout the class 

 from the point of view of comparative embryology. The 

 whole matter is one of great difficulty, and has been neg- 

 lected by insect neurologists; as, however, it is a matter 

 which bears directly upon the subject of this paper I give 

 this summary of our knowledge in so far as it affects the 

 insect protocerebrum. 



* The subject of this paper belongs to the true genus Micropteryx 

 Hiabner. This genus has been referred to in some writings, e.g. 

 Meyrick's Handbook, the Cambridge Natural History, etc., under 

 its synonym Eriocephala Curtis : while the leaf-mining genus erron- 

 eously called " Micro'pieryx " in certain of the same works should be 

 known as Eriocrania Zeller. 



Eriocephala Curtis = Micropteryx Hiibner. 



" Micropteryx" auctt. (nee Hiibner) = Eriocrania Zeller. 



See Tutt, Brit. Lep , I, pp. 129-137 (1899), and Staudinger-Rebel, 

 Cat., II, pp. 246-8 (1901). 



