DIVIDED EYES OF CERTAIN INSECTS 467 



elements with the following exceptions. The cuticular facets 

 of this portion of the eye are much denser than those above the 

 large elements. The iris pigment is black and extremely dense. 

 A heavy black pigment occupies the retinular cells throughout 

 their entire length. Drawing 10 was made from a section 

 that had been depigmented with cone, nitric acid and absolute 

 alcohol, equal parts. The tapetum and the basement mem- 

 brane in this part of the eye are always a little farther apart 

 than in the large element region. Under the trachea and 

 between the nerve strands that lead down from the retinulse of 

 both the large and the small elements are numerous large round 

 or oval nuclei which stain deeply {gn, Figs. 9 and 10, A). No 

 pigment is present around these nuclei. It might be added 

 here that cross-sections of the retinulae of the small ommatidia 

 did not show the number of retinular cells present so clearly as 

 those cut across the large ommatidia. Judging from the num- 

 ber of retinular nuclei however, the number of retinular cells is 

 the same in the retinular of both regions of the eye. 



'BLEPHAROCERA CAPITATA Loew. 



Kellogg, 1903, has called attention to the fact that both males 

 and females of the Blepharoceridas have divided compound eyes. 

 In all the genera described by Kellogg the large facetted area 

 of the eye is dorsal, and the small facetted deeply pigmented 

 area of the eye is lateral. Moreover, the dorsal area of the 

 female eye is greater than that of the male. Males and females 

 of species representing 2 genera (Blcpharocera capitata and 

 Bibioccfihala elcgantulus) were studied by me. The histolog- 

 ical structure of the eye elements in the 2 genera and in both 

 sexes is practically the same. The description and drawings 

 given here are taken from Blefiharocei'a capitata. Fig. 30 is a 

 microphotograph showing the optic ganglion, as well as the dorsal 

 and the lateral eyes of the right side of the head of this species. 

 It will be convenient hereafter to speak of the two areas as the 

 dorsal and the lateral eyes since they are separated from each 

 other by a narrow but distinct groove and the outer lobes of the 



1 1 am glad to make reference to a recent preliminary note on the " Morphol- 

 ogy and Development of the Divided Eyes of Blepharocerca tenuipes' 1 '' by Dr. 

 Wm. A. Riley, in Science, Sept. 7, 1906. 



