THE CANADIAN ENTOMOLOGIST. 191 



considerable friction must be applied to remove them from the surface of 

 the spot. Neither the white nor the black hairs differ from the hairs of 

 similar colour found on the elytra and other portions of the body. The 

 hairs do not ordinarily grow singly, but bundles usually of from two to 

 five spring from the same point, and at the base of each bundle there is 

 a depression in the chitin ; these depressions give the bared chitin an 

 appearance as if etched with acid. The black hairs are dull black, the 

 chitin shiny black. 



Under the "eye-spot" the chitin is somewhat thicker than that of the 

 remainder of the thoracic covering. In common with the chitin of the 

 remainder of the thoracic portion, that of the eye-spot is divided into three 

 layers. The outer layer is quite thin, hard, brittle, opaque and jet black, 

 and probably forms a kind of enamel ; the second layer is thicker, dark 

 brown in colour, and dense and hard ; the inside layer is softer, lighter in 

 colour, and very tough ; it is the thickest of the three layers, and appears 

 to be somewhat vascular near its inner surface, though this appearance 

 may be due to muscular attachments at this point. Directly under this 

 inmost layer are the muscles of the thoracic cavity, in which could be 

 seen the usual respiratory tracheae. No special structures were observed, 

 and certainly nothing suggesting the structures found in luminous organs. 

 Certainly none of the specimens the writer has seen alive has been 

 luminous. 



While these spots appear to be somewhat more than merely a portion 

 of the general scheme of pigmentation, it seems hardly likely they repre- 

 sent any special sense organ. The thickened chitin is opposed to this 

 view. It may, of course, be a rather extraordinary development of pro- 

 tective colouration. In this connection it is of interest to note that related 

 insects are found in various portions of North America, in some of which 

 there is much more of the white colouration, with more pronounced "eye- 

 spots" than in oculatus, while in some others these spots have dwindled 

 until they are mere black specks. 



Somewhat related to this question in Alaus is that of the yellow spots 

 on the elytra of the Indian Buprestid, Chrysochroa ocellata^ which 

 Latreille reported to be luminous, and in which he has been followed by 

 a number of writers. Through the kindness of Mr. H. S. Barber, of the 

 National Museum, I was permitted to examine specimens of this insect 

 and closely-related species. This large and beautiful insect is coloured 

 mainly in rich tones of red, blue and green-gold ; each elytron, however, 

 bears a large, almost circular yellow spot, which lacks the metallic lustre 



