the British, Machilidae. 13 



PetromachiHs longicornis, sp. n. (Pis. III., IV., & V.) 



Length of the body 10 mm. (female). Feelers and tail- 

 process much longer than the body. In segmentation of 

 feelers the segments are Arranged in groups of 12-14 (PI. III. 

 fig. 1 b). The ocelli are dumbbell-shaped and about a quarter 

 of a transverse diameter of an eye apart. The median ocellus 

 is semicircular in form, with straight anterior edge (PI. III. 

 fig. 2). Maxilla with lacinia slightly shorter than galea 

 (PI. III. figs. 6 & 6 a). Palp of maxilla having its six elon- 

 gate segments with proportional lengths 6: 6:6:8'5: 7'5:5'5; 

 antepenultimate segment markedly swollen distally (PI. 111. 

 fig. 6). The last two segments of the maxillary palp present 

 a tapering appearance. The abdominal segments 2—5 bear 

 each two pairs of exsertile vesicles (PL IV. figs. 2, 3, 4, & 5). 

 In the eighth and ninth abdominal segments of the female 

 the processes of the ovipositor have fifty-two segments, each 

 carrying one strong hair on outer margins, and each segment 

 also bearing a whorl of smaller hairs. Gonapophyses on 

 eighth abdominal segment of the male project from mid-line 

 of subcoxaa to about f length of stylets of that segment. In 

 the ninth abdominal segment of the male the subcoxse are 

 produced into very small pointed processes; the gonapophyses 

 do not reach the tips of the subcoxse, stylets long, relatively 

 stout, and with acute apical spines ; penis short, only pro- 

 jecting to -^ length of stylets (PI. V. fig. 9 a). 



Loc. (1) Wasdale Head, Cumberland ; collected by 

 Mr. J. W. Shoebotham, Aug. 1911. (2) Caldey Is., Pem- 

 brokeshire, South Wales ; collected by Mr. P. A. Buxton, 

 June 1914. 



In forwarding his specimens, Mr. Shoebotham mentioned 

 that he found them beneath the top stones of a wall around 

 Wasdale Head House, close to the upper end of Wastvvater 

 ;md the foot of Scafell. The locality of Mr. Buxton's speci- 

 mens (Caldey Island, off South Wales) suggests that this 

 species may be widely distributed in the remoter parts of 

 Great Britain. 



References. 



1913. — Carpenter, G. H. " The Irish Species of Petrobius" Irish 



Naturalist, vol. xxii. 

 1886. — Oudemans, J. T. " Beitrage zur Kenntniss der Thj^sanuren und 



Collembolen." Bijdr. tot de Dierkunde. (Amsterdam.) 

 1809. — Leach, W. E. Article " Entomology " in Brewster's 'Edinburgh 



Encyclopedia,' ix. 

 1873. — Lubbock, J. ' Monograph of the Collembola and Thysanura.' 



Ray Society. 



