Aug. 10, 1888.] 



SCIENTIFIC NEWS. 



i33 



It is well known that the body of caterpillars is com- 

 posed of twelve rings, exclusive of the head. The three 

 first rings support each a pair of pointed legs, which we 

 may call 1, 2, 3 ; then follow two footless rings, 

 followed by four rings bearing each a pair of broad, 

 wart-like legs, frequently armed with hooks, and known 

 as pseudo legs or false legs, because they disappear when 

 the insect assumes its adult condition. We may name 

 them 4, 5, 6, 7. Then come two more rings with- 

 out legs, and lastly the end ring with two membranous 

 feet, the anal legs. Thus, except in some exceptional cases 

 to be mentioned hereafter, a caterpillar has sixteen 

 legs. 



If we take a common caterpillar, and let it creep on a 

 flat slip of wood, held on a level with the eye, we see 

 that the two feet of each pair are always lifted to- 

 gether. 



Suppose a caterpillar at a standstill, with its body 

 stretched out. Its first movement is to detach the anal 

 pair (8), and bring them up to the pair 7 by contracting 

 the two penultimate footless rings which separate them 

 from 7. The pro-legs (4, 5, 6, 7) are then released 

 from behind forwards, in the order 7, 6, 5, 4, and are 

 at the same time pushed forward by slackening the 

 two penultimate footless rings, like a spring set loose. 

 This series of progressive movements of the rings 

 arrives, like an undulation, at the two anterior footless 

 rings. These rings are compressed by the release of the 

 two hinder footless rings, and the pair of legs 4 are 

 thus brought close to the pair 3. This pair is then 

 raised, and in quick succession the pairs 2 and 1. 



We thus understand why the false legs are so robust 

 in comparison with the others. They might be called 

 mooring feet, since they really support the caterpillar and 

 govern its movement. They also secure the cater- 

 pillar in its situation at the moment of its transforma- 

 tion. 



We may now understand why the Cossus and 

 certain other wood-gnawing caterpillars have their 

 false legs membranous, or devoid of hooks. This 

 arrangement is in harmony with their manner of 

 life in the tree trunks in which they excavate their 

 galleries, much as do the larvae of the wood-eating 

 Coleoptera, which have either very short legs or none at 

 all. In compensation, their masticatory apparatus is 

 developed in proportion to its activity — that is, inversely 

 as the locomotive organs. In both cases the same mode 

 of life has brought about similar arrangements in 

 creatures belonging to different groups. The foregoing 

 considerations explain also why, when caterpillars have 

 only three pairs of false legs, the three last pairs remain. 

 If there are only two pairs of false legs we find the two 

 last only, and then the caterpillar, deprived of all inter- 

 mediate legs, arches its body into a loop, so as to approxi- 

 mate the true legs to the false legs. It then detaches the 

 true legs from their foot-hold, and advances them in order 

 to fix them again. This kind of locomotion places them 

 at some disadvantage in comparison with other cater- 

 pillars having sixteen legs. But they have other means 

 of escaping from their enemies. In fact, the caterpillars 

 which feed upon the bark of trees have a grey or greenish 

 colour, which enables them to pass unperceived. They 

 also remain fixed by their hind feet, with the body 

 stiffened, so as to imitate a twig. 



[We can by no means admit that the looper or spanner 

 caterpillars (Geomelrce) are slow in their movements. — 

 Ed. SciENTtnc News.] 



THE ZOOLOGY OF THE BATH 



DISTRICT.— I. 



'T'HE immediate neighbourhood of Bath, although very 

 picturesque and beautiful, is a somewhat disappoint- 

 ing localityfor the naturalist, consisting, as it does, mainly 

 of well-cultivated lands, with no wilder portions, no un- 

 drained marsh or fenlands, no uncultivated moor, or heath, 

 or wood that has remained for centuries unreclaimed and, 

 untouched. The neatly cropped hedgerows, the regu- 

 larly mown railway banks, and even the mud periodically 

 scraped out of the canal — the order and neatness 

 everywhere observable are all great drawbacks to the 

 collector of zoological treasures. 



The most promising features are the Avon and the 

 Kennet and Avon Canal above Bath, and the valley of 

 the Avon below, towards Bristol, also a few small 

 patches here and there, as on Lansdown, Claverton 

 Down, etc. ; better still, but rather out of the district 

 lie the turf moors of Shapwick and Glastonbury. These 

 are happy hunting-grounds for the entomologist or 

 student of other invertebrate branches, mollusca, etc., 

 and will yield rich harvests to those who will work them 

 carefully, and are also the spots most likely to be visited 

 by the migratory birds and other accidental visitors. 



Tobeginwith the higher branch — namely, mammalia — 

 of the ordinary ferse,the badger (Meles la.xits) and the otter 

 (Lulra vulgaris) seem commoner than farther east. The 

 stoat, or ermine (Mustela crminea), and the weasel 

 (Mustela vulgaris) are very abundant ; curiously enough, 

 some of the country folk invariably reverse the names of 

 these two species, calling the smaller one the stoat, and 

 the larger one the weasel. 



The polecat {Mustela putorius) is getting almost 

 extinct in the district ; 1879-80 is the last reliable record 

 of its occurrence ; thirty years ago it was quite common, 

 and has been seen in very severe weather, hunting in 

 packs ot ten or more individuals. 



Of the bats seven species occur. The noctule(J "espertilio 

 noctula) is somewhat rare. The pipistrelle (J 'espertilio 

 pipidrellus) is also rare, although the commonest bat in 

 many parts of England. The whiskered bat (Vespertilio 

 myslacinus), "said to be very rare in England," is quite 

 common round Bath in the roofs of old houses. The 

 reddish-grey bat (Vespertilio nattcreri) also occurs, 

 although rare; two specimens may be seen in the 

 '•' Duncan Local Museum," at the Bath Literary Institution. 

 The eared bat (Plecotus aurilus) is fairly common. The 

 great horse-shoe bat (Rhinolophas ferrum-equinnm) and 

 the lesser horse-shoe bat (R. hipposideros) both occur in 

 stone-quarries ; the latter is much the rarer of the two. 



Mr. Charles Terry, F.R.C.S., in "Wright's Historical 

 Guide to Bath " (1864), gives a list of the fauna within a' 

 radius of six miles of Bath. He therein mentions six 

 species of bats, one of which ( Vespertilio emarginatus), 

 the notch eared bat, is most likely a mistake ; he makes 

 no mention of V. nattereri, or V. mystacinus. 



Of the Insectivora, the mole (Talpa vulgaris), the 

 hedgehog (Erinaceus Europtzus), and the common shrew 

 (Sorex tetragonurus) are abundant. The beautiful little 

 weter-shrew (Sorex fodiens) also occurs, but is rather 

 scarce; this species is easily distinguished from the 

 former by its rather larger size and by the distinct line 

 of demarcation between the dark upper portion and the 

 light (almost white) lower portion. The variety which 

 has been described as Sorex remifer is mentioned by Mr. 

 Terry in his list. 



