MR. LUBBOCK ON THE THYSANURA. 599 



claw, five or six small teeth ; the lesser claw is lanceolate in form, but with the lower 

 margin straighter than the upper one, and has a single, very minute tooth on the upper 

 side. The second and third pairs of feet much resemble the first ; but the small spine 

 on the lesser claw of the third pair is rudimentary or altogether absent. On the basal 

 part of the caudal appendage are, as in M. phimhea, nine black spines. In that species, 

 however, they are simple and short, while in the present they are much longer. The 

 four first form a somewhat curved line ; the remaining five are arranged in a straight 

 row, and have small processes at the side ; the apical spine and the penultimate are the 

 largest. 



The form and arrangement of these spines, and the structure of the feet, satisfactorily 

 distinguish this species from the preceding. If in M. minor, which is smaller than 

 M. phmibea, these caudal spines had been smaller than in that species, and the spines on 

 the feet had been less nunierous, we might well have supposed that these differences 

 depended on age, and were therefore of no value as specific characters. I was, indeed, 

 for a long time disposed to consider M. minor as being merely the young stage of the 

 larger 3£. phimhea ; but the large specimens are comparatively so rare, that, for this 

 reason alone, such an opinion seemed to me untenable. This is, I think, confirmed by 

 the structure of the feet and of the caudal appendage. 



With the specimens above described are others which are narrower, and, without the 

 scales, of a yellow colour. When placed in spirits, also, these two forms behave dif- 

 ferently ; the first swell, and the intersegmental membranes are more or less exposed, 

 while the other variety retain their original form. The structure of the antennae, the 

 feet, and the caudal appendages is, however, so similar in the two forms, that I do not 

 feel justified in separating them specifically. 



Lepidocybtus. 



Lepidocyrtus akgentatus, Bourlet ? (PI. LIX. figs. 16, 17.) Body cylindrical, the third 

 segment decidedly narrower than the second and fourth ; silvery, with brilliant me- 

 tallic reflexions. Eyes situate on a black patch. Antennae and legs grey, the latter 

 paler than the former; basal segment of antenna short, second and third equal, 

 and about two-thirds as long as the apical. Caudal appendage pale, reaching to 

 the ventral tube. Thorax with a tuft of short hairs in front ; posterior segments of 

 abdomen with long, scattered setas, some of which are waved. 

 Length ^\h. of an inch 



Occurs all throvigh the winter, from November, and perhaps earlier, to April, under 

 logs of wood in Kent. 



The mandibles have respectively four and five teeth. The labrum is pear-shaped. 

 The feet have each a single tenent hair of the usual form. The large claw has two small 

 teeth on its under side. The small claw is lanceolate. The first abdominal segment is 

 decidedly narrower than those on each side of it. 



It may well be doubted whether this is really the L. aryentatusot Bourlet, his descrip- 

 tion being very brief and unsatisfactory. He says, " Thorace minus elato, corpore squamis 



VOL. XXIII. 4 L 



