SCIENCE-GOSSIP. 



101 



S. scoticum has the vertex of the head slightly 

 arched, the eyes large and prominent ; the body is 

 nearly as long as broad, almost circular. It is 

 hairless; central line spineless; the two segments 

 prior to the last are provided with short, straight 

 spines at the sides ; the wing-cases are very long, 

 reaching nearly to the last segment ; the side 

 pieces of the caudal apparatus are slightly longer 

 than the middle piece. Generally distributed in 

 stagnant ponds. The nymphs of this genus are 

 the smallest of the Libellulinse. 



So far as I am aware, the eyes of the members 

 of this group have never been accurately described, 



indistinct, being visible only under a high power of 

 the compound microscope. A reference to the 

 figures will render this matter more clear. 



The nymphs of the sub-family, Corduliinae, are 

 of singular aspect, with nearly naked, sub-cylindrical 

 bodies armed with stout hooks or spines on the 

 back and sides. 



SOMATOCHLOR'A metallica.— The head of this 

 nymph is nearly pentagonal, the angles slightly 

 rounded, and has a wavy ridge fringed with fine 

 bristles behind the eyes. The tenth segment is 

 very short. Dorsal hooks occur on the third to 

 ninth segments, and lateral spines on the eighth 



<x \y 



Fig. i represents Libelhda depressa, after Dufour; a shows a fore-foot; b, the helmet-shaped "mask"; and i and (J two 



aspects of the peculiar eyes of the Libellulinae. Fi j. 2 is of Orthetrum cancellatum. 



Fig. 3 of Sympetrum vulgatum, a, the upper, and b, the underside. Fig. 4 shows Lcucorrhinia pectoralis. 



Fig. 5 represents Somatochlora metallica, figs. 5A and 6 showing the bodies of that species and Cordulia anea. 



previous writers speaking of them as being mere 

 bead-like projections, occupying the upper four 

 corners of the head. On a cursory inspection they 

 appear so, but on a closer examination they are 

 seen to be of a most peculiar shape, a kind of 

 twisted broad-based cone, somewhat rounded at 

 the apex, and with a slight backward prolongation 

 to the disc of the head. These characters are 

 extremely difficult to see clearly in living specimens; 

 but spirit-preserved larvas show the form of the 

 eyes very well, the chitinous outer walls being 

 thrown in sharp relief against the partly-bleached 

 skin of the head. The facets are very minute and 



and ninth segments ; the sixth carries a ventral sac. 

 The only localities that can be mentioned for this 

 nymph is Rannoch Wood, in Perthshire, and, I 

 believe, the Lakes of Killarney, the imago being rare. 

 CORDULIA anea is extremely like the last. 

 Dorsal hooks occur on the same segments, but are 

 thicker, except on the ninth segment, where they 

 are only indicated. The chief differences are : 

 raised line on head less prominent and finer than 

 in metallica ; two black transverse marks on each 

 side of head, one being near the foremost ocellus, 

 the other above the antennal base. The thorax 

 has a black dorsal band, and two cross markings 



