5° 



HARDWICKE'S SCIENCE-GOSSIP. 



Pa-la maxima, Scopoli ("the stone- fly " par ex- 

 cellence). In point of size this species and the one 

 following run very close, but maxima is generally 

 considered to be somewhat the larger, some speci- 

 mens measuring nearly three inches across the 

 expanded wings. The usual length is about twelve 

 lines, the wing expanse in the female being about 

 two inches eight lines, and in the male about 

 one inch nine lines. The wing nervures are very 

 dark. 



As regards the present species, Dr. Brandt has 

 raised a point of great interest to biologists. After 

 having noticed rudimentary ovaries, etc., in a male 

 larva, he was greatly astonished to observe the same 

 structures in a male imago, from a different locality. 

 He asks, can he have observed only a monstrous 

 individual in each case, or is rudimentary hermaphro- 

 ditism a rule with the species? 



Perla margiiiata, Muraldt. Individuals of this 

 species are found of large size. One specimen in 

 the British Museum measures two inches eleven 

 lines across the expanded wings. The length is 

 usually about eight lines, and the wing expanse ( 9 ) 

 about two inches. The measurements of the male 

 are much less, the wings being often atrophied. The 

 male is generally lighter in colour than the female, 

 but the markings vary but little. Both sexes are 

 fairly common along the banks of streams at the end 

 of spring. The Rev. J. G. Wood says: "The egg 

 cluster of this species is as large as a swan-shot, and 

 nearly as black." According to Curtis, the cast 

 pupa-skin is beautifully spotted. 



Perla cephalotes, Curtis. This insect is remarkable 

 for the extreme disproportion that exists between the 

 male and female ; moreover, the wings in the male 

 are reduced to mere rudiments. This species is 

 somewhat like the last, both in size and colour, 

 though cf specimens of marginata usually have the 

 wings long. The colour of the prothorax will 

 separate them. It appears in summer. 



Chloroperla rivulorum, Pictet. This species is to 

 be distinguished from the next by the generally 

 distributed brown tint, by the head being brown 

 in the middle, with a well-marked blotch in the 

 form of a horse-shoe. Appears in summer by 

 the sides of mountain streams. Transformations un- 

 known. ■ 



Chloroperla grammatics, Poda. Mr. Parfitt says 

 of this insect, "Very abundant aloDg our rivers and 

 streams (in Devonshire) from May to October. It 

 varies greatly in size and colouring, so as to lead one 

 to think that there are two or three species collected 

 under one head." Of these varieties, the reddish 

 rufescens is the most aberrant. This species also 

 bears a horseshoe-shaped blotch on the head, but 

 it is isolated. The palpi are prominent. The 

 imagines emerge in April, and are widely dis- 

 tributed. 

 Isopteiyx torrentium, Pictet. Somewhat rare ; 



frequents wood-stacks ; emerges about May. Larva 

 and pupa unknown. 



Isopteiyx Burmeisteri, Pictet. Abundant in the 

 north " by the side of every water " (Mr. J. F. X. 

 King) ; common in Ireland ; probably mixed in 

 cabinets with /. tripunctata. 



Isopteryx tripunctata, Scopoli. Smaller than the 

 preceding. The palpi are very prominent. This 

 is the "yellow Sally " of anglers. Larva unknown. 



Isopteiyx apicalis, Newman. The smallest species 

 of the genus. The palpi are very prominent. Larva 

 unknown. 



Capnia nigra, Pictet. There is a record in the 

 " Canadian Naturalist," of enormous numbers of 

 this species appearing on the snow on the Riviere 

 du Loup, Canada, in the month of March a year or 

 two ago. Bethune, also, in the " Canadian Ento- 

 mologist," speaks of the occurrence every spring, of 

 swarms of this small perlid on the River Credit, in 

 Canada, and of its frequently being found on the 

 surface of snow. I believe the same thing occurs to 

 some extent in Scotland. 



This species, the only British one of the genus, 

 rolls its wings into a half-cylinder around its body, 

 thus mimicking certain Nemourae. It is difficult to 

 capture without damaging it in some way. It flies 

 but seldom, and then swiftly for short distances 

 among the stones at the water's edge. It is ap- 

 parently confined to northern limits, and does not 

 seem to occur in Britain in any great numbers. 



Ttzniopteryx nebulosa, Linne. This is the largest 

 of the known species of the genus. Anglers have 

 named it the "red upright." Parfitt, speaking of 

 this species in Devon, says, " very scarce." He also 

 writes, "The larvae of this species live among the 

 stones, of which the weirs on the Exe are built, and 

 where the water rushes over with great force. When 

 about to undergo the last change, or rather the 

 emergence of the imago, the subimago creeps up 

 the wood-work of the weir or the sluice-gates, and 

 grasps the wood very firmly, with its legs out- 

 stretched, and the sharp claws of the tarsi firmly 

 pressed into the wood. The head is first ruptured ; 

 the skin then parts along the back from the pressure 

 within, as far as the base of the wing-cases ; the 

 insect gradually emerges, leaving its old skin to dry 

 on the wood-work. The difference in the colouring 

 in the subimago and the perfect insect is very striking. 

 In the former, it is shining black-brown. The face 

 is ornamented with a white mark in the form of a 

 Greek or an Egyptian vase, having two curved 

 cornutoe for the handles, mouth white, with ferruginous 

 jaws, antennce yellow. The thoracic region is macu- 

 lated with white, the tips of the wing-cases are 

 whitish ; the abdomen has two rows of angular white 

 spots on each segment, setae pale yellow, legs whitish, 

 femora dusky beneath. All the tibiae, and especially 

 the posterior, are provided with a row of long ciliae 

 on the outside, to assist them in swimming." The 



