SCIENCE-GOSSIP. 



131 



species are never found in the same stream, 

 although frequently occupying adjacent waters. 



Wc next arrive at the sub-family Ccenagrionina?, 

 which includes all the smaller species breathing 

 by caudal lamella: only. The lamellar circulation, 

 first noticed by Dr. Carus, is remarkably distinct. 

 Signor Roster has done most towards describing 

 the nymphac. The nymphs of Ennalagma are quite 

 unknown, as are also several species of other genera. 



than in other known species. There are two small 

 tubercles and a blackish line occipitally. The 

 swollen final body-segment bears two lateral 

 prickles. The large lamella*, rounded apically, 

 arc much veined. The mask is characteristic. 

 Two imagos only have been taken, both in the 

 New Forest many years ago. 



L. barbara. Yellowish green. Head elongated, 

 somewhat like that of L. viridis, with some spots 



-if > 



7 



> 



> 



10 



IZ IS 



Masks of Dragon-Fly Larvae. 



These Figs, show the heads («), leg-base processes (b) and caudal points (c) of 10, Brachytron pratense ; n, JEschna mixta ; 

 12, JE.juncea; 13, M.cyanca ; 14, /E. grandis ; 15, JE. rufescens. 



The structure of the mask, being constant, offers 

 the most distinctive characters ; other parts, such 

 as the caudal lamellae, vary considerably. The 

 genus LESTES heads the list, its characters are : 

 antennal joints nearly equal, mask long and 

 narrow, the mandibles deeply trifid, abdomen 

 nearly cylindrical, and (except in L. dryas) the 

 segments with a spine on each side. The head is 

 hollowed out where attached to the thorax. Roster 

 compares it to that of the hammer-head shark, and 

 further remarks that Rondelet figures, under the 

 name of Squilla fluviatilis, an odonate larva, the head 

 of which is so exaggerated that it is easy to recognise 

 a Lestes, the species probably being L. viridis. 



LESTES dry as (L. nympha of Selys), according to 

 Hagen, has the mask very long and narrow, 

 extending to and between the hind legs. The five 

 last but one abdominal segments have short 

 straight spines at the sides. The wing sheaths are 

 shorter than in Ccenagrion, and the cauda? are long 

 and broad. This is local and almost confined to 

 the south. It also occurs in Ireland. 



L. viridis is of a dull yellow, with abdominal 

 segments beautifully spotted. The mandibular 

 characters are shown in accompanying figure. 

 The legs are relatively long and are darkly spotted. 

 The cauda? are slightly lengthened. One imago is 

 said to have been taken many years ago in the New 

 Forest. 



L. virens is yellowish green, obscurely punctured, 

 and minutely haired. The head is more globular 



and two stria? occipitally; abdomen swollen; the 

 segments laterally spined, spotted above ; a small 

 dark line on each side of median line ; two minute 

 points above bases of cauda?, which are equally 

 very long and pointed, and spotted with two 

 dark transverse fasciae. I give a figure of the 

 labium. No undoubtedly British specimen of the 

 imago exists. 



PLATYCNEMIS pennipes is dirty yellow in 

 colour, slightly hairy. It usually darkens some- 

 what before undergoing its metamorphoses. The 

 upper head is indented, and between the eyes are 

 two black lines, beneath which are antenno-basilar 

 tubercles. The third joint of the antenna? is 

 longest. The thorax, like that of Agrion, is 

 wide with well-marked divisions, and a sharp 

 spinous process occurs on each side. The conic 

 abdomen is unicolorous, unspotted and spineless, 

 but with two small tubercles terminally. The 

 lanceolate cauda? are sub-equal, the central one 

 being the most veined. The form of mask differs 

 greatly from that of Lestes, it being shorter and 

 wider, sub-triangular, and has characteristic hairs 

 at the sides ; the trifid mandibular portions show a 

 false joint ; the median piece is somewhat unequal 

 apically, and the base is provided with five 

 chitinous tubercles. This species crawls very 

 slowly along stream, pond and canal beds, or on 

 aquatic plants, seldom using the caudal lamella? as 

 organs of locomotion. It has not been recorded 

 from Ireland. (To be continued.) 



