50* EXTERNAL ANATOMY OF INSECTS. 



Copris; it goes beyond the half in Ateuchus; and in Rys- 

 sonotus MacLeay (Lucanus nebulosus K.) it quite divides 

 the eye into two a , as I before observed. In Lticanus, 

 Passalus &c. it projects before the eye into an angle ; in 

 Lucanus femoralis nearly into a spine ; but in Lamprima 

 and CEsalus it does not exist. The part, also, that enters 

 the eye in the Capricorn-beetles may be regarded as a 

 kind of canthiiS) though it is merely a dilatation of the 

 front. 



4. Stemmata b . — Having given so full an account ot 

 the kinds and structure of the ordinary eyes of insects, 

 you may perhaps expect that I should now dismiss the 

 subject : you would, however, have great cause to blame 

 me, did I not make you acquainted with a kind of auxi- 

 liary eyes with which a large portion of them are gifted ; 

 I mean those pellucid spots often to be found on the poste- 

 rior part of the front of these animals, or upon the vertex, 

 frequently arranged in a triangle. These, Linne, from 

 his regarding them as a kind of coronet, called Stem- 

 mata. They have been of late denominated Ocelli ; but 

 as this latter term is also in general use for the eyelets on 

 the wings of Lepidoptera, I have adhered to that of the 

 illustrious Swede. Neither he nor Fabricius has ex- 

 pressed any opinion as to the use of these organs ; but 

 Swammerdam and Reaumur were aware that they were 

 real eyes. The former found that there are nerves that 

 diverge to them though not easily traced, and that they 



a This circumstance proves that Mr. W. S. MacLeay is correct in 

 considering this as a subgenus; but it militates against its being 

 connected with Lamprima. 



" Plate VI. Fig. 4, 10. VII. Fig. 1, 2, 4. XXVI. Fig. 39-42. i. 



