bearing on the origin of Insects. 155 



and of the thoracic stornniii and its a})pendages of 

 Macliilis with those of Blutta and Lepisina appears to 

 me rather in favour of the vieAv that the thoracic exopo- 

 dites of the former, if represented at all in its maxillfe, 

 are represented by the whole palp in both pairs, and that 

 the outer of the three lobes into which the less modified 

 second pair is on each side divided perhaps answers to a 

 thoracic leg, while the middle and inner ones are pro- 

 cesses of the two terminal joints of the protopodite, the 

 first joint * of this having coalesced with its fellow of the 

 opposite side to form the great azygous basal plate, the 

 ' submentimi ' of Blatta. 



The presence of a similar appendage on the inner, 

 instead of the outer, side of the very base of the first free 

 joint t of all the legs except, according to Lubbock, the 

 first pair in the myriopod genus Scolopendrella,\ suggests 

 the suspicion that the limbs of myriopods are not strictly 

 homologous with those of insects, but that they correspond 

 with the rudimentary appendages of Mac hi /is, and are 

 consequently exopodites, the appendages of the legs in 



* The following pair or pairs of sclerites have not coalesced to form a 

 'mentum' as in lilatta, the two inner lobes of the jaw of which have been 

 lost in the greater coalescence of parts that has taken place therein, the 

 outer one alone remaining as the paraglossa;. 



f This is here the fifth from the distal end of the limb. Two short 

 joints, represented in this small and excessively-fragile creature by two 

 scarcely perceptible folds, seem to be interposed, as in Scolopendra, 

 between this first free basal joint and the sternum, and the appendage 

 springs from the notch between the two folds and the first free basal joint 

 of the limb. Scolopcndrella differs from all myriopods known to me, 

 and agrees with Peripatvs and all insects in having legs terminated 

 by two curved claws. In many of the legs of my specimens of Pt'vipafus 

 {P. Mo.selei/i, with 21 — 22 pairs of walking-legs, from S. Africa), I find, 

 between the first joint and the foot-cones, on the under or inner side, a wai't 

 larger than the rest and terminating in a smooth and very low papilla, dis- 

 tinctly marked off from the wart by a circular groove. It occupies the same 

 position relatively to the leg, and may represent the endopodite of Scolo- 

 jjcndrella. Scolopendrella has very remarkable antenna; ; they may be 

 compared each to a series of glass cups strung upon a delicate hyaline 

 and extensible rod of uniform thickness throughout; so that, like the body 

 of the creature, they shrink enormously when the animal is irritated or 

 thrown into alcohol, and they then possess scarcely two-thirds the length 

 they have in the fully-extended condition, their cup-like joints being 

 drawn close together, one within the other. Perlpatvs, lapijx, many (if 

 not all) Homoptcra, and the S. Asiatic relatives of our common Glomeris 

 have all more or less extensible anteuiiaj. 



\ This curious myriopod is conmion all over Painswick Ilill, Glouces- 

 tershire, where it lives beneath stones which have long lain, as their 

 weathered or lichen-covered to]3S testify, deeply buried in the turf. The 

 rarer and still more fragile Campodca lives in similar situations. I ob- 

 tained all my specimens of both genera iu the months of April and May. 



