JOIs^ES— TEATLS, TEAGKS, ANT) SURPACE-MAREIXGS. 



135 



thougli they may have been due to birds. I may mention, that a 

 friend in India (Mr. E. N. Mantell, since deceased) described to me 

 in a letter, some large, broad, trifid markings that he saw on the sand- 

 banks of the Ganges ; they were of this shape (fig. 7), shallow, and 

 with a well-definededge. Tracing v 

 the track to where the sand was ^ >\ 

 wet, he found them take the un- V\ 

 mistakeable and unpretending 

 shape of ordinary bird-tracks (fig. \ 

 8} ; " the sole and sufficient rea- --^^J' 

 son," said he, "of their gross ex- 

 aggeration was the action of the -^^S- 

 wind on the fine dry sand." Trying prints of his own hand, he saw 

 them slowly become augmented into broad caricatures of a hand-print 

 by the same natural process. 



* On the figured slab of Wealden rock, from the Upper Hastiogs 

 Series, near Cuckfield, Sussex (PI. YIL), we have sun-cracks, raised 

 gallery-markings, and many obscure trails, some corrugated, some 

 smooth. It is possible that, as a friend has suggested to me, some of 

 these may be the marks of roots of aquatic plants ; but there is no 

 direct evidence on the subject. Eoot-like markings, however, small, 

 vertical, and numerous, occur abundantly in the Hastings sand-rock, 

 as pointed out to me by my friend Mr. J. Morris (see fig. 9). 



During the autumn of the same year as that in which I collected 

 the recent trail-marked mud in the Isle of Wight, I was in the Weald 

 of Kent, and, examining a brick-field, I saw a pond lessened by 

 drought, and on its mud were prints of a dog's feet, small hollow 

 trails, and convex galleries, such as those before noticed (fig. 10). 

 The roofs of some of these last were so thin they were split, and in 

 some cases removed. Besides the markings above mentioned, the dry- 

 ing clay had another iuteresting feature, namely, a partial coating of 

 minute globular bodies (fig. 10 a), mostly lying closely packed in single 

 layer, but sometimes crowded irregularly, and occasionally scattered 

 about loosely. These are of the same colour as the clay, and are 

 probably the ova of the Boat-fly {Noionectd), thinly coated with clay ; 

 and their interest lies in the fact that in Mexico allied insects are 

 known to lay a profusion of large ova in the Lake of Tezcuco, and 

 that there they become petrified into an oolite. The fact has been 

 described by M. Yirlet d'Aoust, in the ' Bulletin de la Soc. Geol. de 

 France,' 2e Ser., vol. xv. p. 200, etc., 1858, who, noticing the oolitic 

 structure of the recent limestone on the margin of the salt-water 

 lake of Tezcuco, near Mexico,* learnt from Mr. J. C. Bowring, the 

 manager of the salt-works there, that the oolitic granules were nothing 

 more than the eggs of certain insects, encrusted and cemented toge- 

 ther by the calcareous sediment of the lake. The eggs, too, being 

 attached by little stalks or pedicels, are the more readily coated with 

 the lime all over, and keep their relative position the more firmly. 



* See the memoir for some interesting information on tlie relationships of the great 

 freshwater and salt lakes of the Mexican plateau ; also, E, B. Tylor's ' Anahuac,' 1859. 



