222 



HARDWICKE'S SCIENCE-GOSSIP. 



effect, judging from a aeries of gipsy moths 

 {Hypogymna dispar) I bred in this country from 

 southern parents. Dwarf butterflies are often taken 

 at large, and the process in no way impairs the 

 faculties of the individual. Since caterpillars only 

 feed in bright light, the reason why British butterflies 

 and moths that have left colonies in Italy should 

 invariably be giants of their kind and appear oftener 

 in the year, is easily seen. Indeed the curious 

 circumstance is that the cabbage plant should 

 nourish two nearly related white butterflies that differ 

 so much as [to size. As regards the smaller whites, 

 with all this seasonal dress in common and an 

 identical variation on the under surface of the wings, 

 from pale sulphur to canary yellow, we have, as I 

 said before, a radical difference, namely in the appear- 

 ance or absence of the black rays. Sometimes these 

 dark markings only appear, in the green-vein, at the 

 base of the under wing beneath, and then it resembles 

 most its congeners. If we accept this as a primordial 

 form of the whites, it remains to discover the 

 conditions necessary to produce it ; it is not seemingly 

 a vernal variation, since I take it in August. 



But let us leave this topic, and take a stroll in the 

 cool down to the mill beneath the castle, where an 

 American pond weed {Anacharis alsinastrum) may 

 be observed with a freshwater Asiatic mussel 

 (Mytilits polymorphus) clinging to its tangles ; both 

 of which, of late years, have largely propagated in the 

 Wey. I should likewise like to visit the spot on the 

 Hog's Back, where a gentleman picked last year an 

 American weed, the Claytonia pcrfoliata ; or to mount 

 to the bank where the spotted dead-nettle (JLamium 

 macitlatuni) is growing wild ; we shall find near it a 

 large shrubby spurge that has lately made itself ,at 

 home on the building plots. Time forbids us to 

 search for the grape hyacinth out at Merrow, or the 

 Roman snail {Helix pomatid) in the chalk pits, or to 

 look for that pink colony of the Helix cantiana a 

 friend asks word of. Indeed this old place should 

 likewise be quite a choice locality for garden sports. 

 Was it not at Guildford that the Queen of Henry 1 1 1. 

 kept an herbarium, and from the neighbouring 

 Waverley, fifty years after, that a prize carnation 

 was sent yearly to the Abbot of Dinan in Normandy? 



Pupa Digging. — There is no better way of col- 

 lecting lepidoptera than hunting for their chrysalides. 

 The implements required are simple ; a common 

 garden-trowel, a short, strong, blunt knife, and a tin 

 box. Thus equipped, take your way about the middle 

 or end of October to the nearest wood, and with the 

 aid of your trowel carefully peel away the turf from 

 the bottom of the tree-trunks. Many chrysalides will 

 be found just under the turf, others are a few inches 

 deeper. It is of course unnecessary to warn you to 

 dig carefully, lest you risk doing some rarity a mortal 

 injury. — Albert H. Waters, B.A. 



A CHAPTER ON BRITISH FOSSIL BIRDS. 

 By Arthur, Smith Woodward. 



THE remains of all kinds of vertebrate animals 

 have a very small chance of being preserved in 

 a fossil state, owing to the very numerous ways in 

 which they are liable to annihilation before entomb- 

 ment, and owing also to the fact that an exceedingly 

 large number of the relics are those of air-breathers 

 that do net come within' reach of any transporting 

 currents, by which they can be carried to some 

 suitable spot and buried in sediment. But of all 

 groups of the most highly organised division of the 

 animal kingdom, the class of birds is the least likely 

 to be well represented, in the palaeontological record. 

 The skeletal structures of the feathered tribe are so 

 extremely fragile that even if an individual after 

 death does happen to find its way into water, which 

 would eventually bring it to a place of entomb- 

 ment, it not only, like all other vertebrate remains, 

 has all the risks of being devoured by some predaceous 

 fish, but is also liable to annihilation from other 

 causes, in consequence of its delicate organisation. 

 Thus, our imperfect knowledge of the avi-fauna of 

 any area, during any geological epoch, can easily be 

 accounted for ; and when we look at all sides of the 

 question, we really must wonder how fortunate we 

 are in being able to know anything at all on the 

 subject. 



It is very rarely that the skeletons of any but the 

 natatorial birds {Aves aquatiecz, of Nitzsch) can be 

 entombed in marine deposits ; sometimes, remains of 

 the Aves terrestres, and aereee, may reach estuaries ; 

 but usually those that do find their way into river 

 waters are buried in the terraces and valley-gravels, 

 which, from their limited extent, are seldom found 

 of greater antiquity than the most recent (Pleistocene) 

 geological times. Cavern deposits sometimes yield 

 a number of bird-remains, but these accumulations, 

 like river-terraces, are generally of such small dimen- 

 sions, that they cannot often survive denuding agencies 

 for any long geological period. 



For these and many other reasons, it is no long task 

 to summarise all that is known concerning the birds 

 which have existed in the British area of the globe 

 during past geological epochs. The remains of 

 scarcely any examples have been noticed as occurring 

 in the British Mesozoic deposits ; a few more have 

 been detected, and with greater precision, in the Lower 

 Tertiaries (London Clay of Sheppey, and Headon 

 Series of Hordwell Cliff) ; some difficultly-determin- 

 able fragments of the avian skeleton have been found 

 in the Pliocene Crags ; several species have been 

 recorded from cavern deposits ; and, lastly, some 

 exceedingly interesting facts concerning the ornitho- 

 logy of this part of the globe in the most recent times 

 have been obtained by a study of numerous bones 

 found in fluviatile accumulations and peat-bogs. 



