OCTOBEE 1. 1890.] 



KNO^A^LEDGE 



223 



T 



^^ AN ILLUSTRATED ^V 



MAGAZINE OF SCIENCE 



SIMPLY WORDED— EXACTLY DESCRIBED 



LONDON: OCTOBER 1, 1890. 



CONTENTS. 



Giant Land Reptiles. By R. Lydekker, B.A.Cantab. 



The Bed-Bug.— U. By E. A. Butler 



Village Communities. By Canon Isaac Taylor. Litt.D., 

 LL.D ". 



Notes on Phyllotaxy, or the Mathematical Arrange- 

 ment of Leaves and Branches. By .1. Pentland 



S.MITII. B.A., B.Sc. 



On the Conservation of Energy. By ,T. J. Stewart 



The Cayenne Eclipse Expedition 



Notices of Books 



E. Barnard ; G 



Letters :— F. Pincott ; E, 

 J. E. (ioRE; G. Daniel 



Numbering the Dust of the Air 



F.R.S.E 



The Face of the Sky for October 

 Sadler, F.R.A.S 



Whist Column. By W. Montagu Gattie 



Chess Column. By I. Gunsbebo 



E. Favene: 



By Dr. MiPherson, 



By Herbert 



240 

 241 



GIANT LAND REPTILES. 



By R. Lydekker, B.A.Cantab. 



THE traveller from London to Hastings, by way of 

 the South-Eastern Railway, on leaving the tall 

 chalk hills of the North Downs, some short dis- 

 tance to the north of Sevcnoaks, enters suddenly 

 on a more open district, known as the Weald of 

 Kent and Sussex. This district presents many remarkable 

 and peculiar features, one of the most striking being the 

 great prevalence of oak-trees in those parts having a 

 clayey soil ; and the traveller will not fail to notice that, 

 in place of the chalk which he has just left, all the rocks 

 of the district consist of alternations of beds of clay, sands, 

 and sandstone. These peculiarities in the structure of the 

 rocks continue the whole way to Hastings ; and the tall 

 cliffs of sandstone, on one of which arc perched the ruins 

 of the ancient castle, rising to the eastward of that town, 

 and forming the most prominent features in the land- 

 scape of the neighbourhood, are too well known to require 

 further mention. The whole of this extensive series of 

 rocks, which attains a vertical thickness of many hundred 

 feet, and has been much worn away by atmospheric 

 action, and also thrown into a series of folds, is con- 

 siderably older than the chalk, from which it is separated 

 by the beds known as the Upper Greensand, Gault, 

 and Lower Greensand, and is coUectixcly known as the 

 Wealden series, or formation. Listcad of having been 

 formed, like the overlying chalk and othei- deposits, at the 

 bottom of an ancient sea, the whole of the ^\'ealden beds 

 are of purely fresh-water origin — a circumstance abundantly 

 proved by the fossils found in the beds theniselves, whicji 



comprise fresh-water shells, and the remains of land plants 

 and land animals, to the total exclusion of all marine 

 organisms. It is, indeed , probable that the area of the 

 Wealden strata, which originally extended fi-om Kent to 

 the Isle of Wight, once formed the delta of a mighty 

 river, flowing into the North Sea, and draining a very 

 considerable portion of Northern Europe, during that 

 period of the Secondary epoch of the geological scale 

 immediately preceding the one in which the greensand 

 and chalk were deposited. 



Apart from its many other points of interest to the 

 geologist, as well as those which it presents to the botanist 

 and the archiBologist, the Wealden area has an especial and 

 unique claim on the attention of the palaeontologist. It was, 

 indeed, mainly from the huge fossil bones obtained during 

 the earlier decades of the present century fi-om these 

 deposits, by the late Dr. Gideon A. Mantell, of Lewes 

 (whose perseverance in the collection and description of 

 these remains during the hard-earned leisure of a laborious 

 medical practice cannot be too highly praised), that our 

 first definite knowledge was acquired of that wonderful 

 group of extinct land reptiles forming the subject of the 

 present article. These creatures, for which Sir Richard 

 Owen has proposed the name of Dinosaurs (Gr. drinos, 

 terrible, and saiiros, a lizard), were certainly worthy of 

 their name, for it is impossible 

 to conceive more appalling mon- 

 sters than those which wo propose 

 to briefly notice. 



The "labours of Dr. Mantell 

 were mainly devoted to the 

 Wealden rocks near the \-illage 

 of Cuckfield, in the neighbour- 

 hood of Brighton, where this 

 enthusiastic worker obtained a 

 great number of bones of teeth, 

 which are now preserved as some 

 of the most valued treasures of 

 the British Natural History 

 Museum. These specimens, im- 

 perfect though many of them were, 

 F ■ 1 — o ■ ■ s enabled their discoverer to affirm 



'the CRowroF A Too?H that the old delta of the Weald 

 OF THE Igoanodon. WES oucc inhabited bv scveral kluils 



of extinct reptiles, all of which 

 were totally unlike any existing forms, and some of which 

 vastly exceeded in size any land animals now living upon 

 the earth. By patient research Mantell was enabled to 

 arrive at a fair approximation of the general form of ibe 

 skeleton of some of these strange and uncouth inhabitants 

 of a former world ; but from the fragmentary condition 

 of the remains of other species, and the extreme pecu- 

 liarity of their structure (as now known by entire speci- 

 mens), he never even dreamt what weird creatines he had 

 been the means of first bringing to the notice of the 

 scientific world of his time. 



One of the first, and at the same time one of the 

 strangest, of these Giant Reptiles discovered by ^lantell, 

 was first definitely determined from the evidence of the 

 detached teeth, which are of not uncommon occurrence in 

 some of the Wealden beds, and one of which is shoA\-n of 

 the natural size in the accompanying woodcut (Fig. 1). 

 These teeth have peculiarly flattened crowns, with well- 

 marked riutings on the outer surface, and with serrated 

 lateral edges. In numy of them the tops of the crowns 

 are found to be worn quite flat by mutual abrasion ; and it 

 then became evident that these teeth indicated a reptile 

 of herbivorous habits, which was also of gigantic size. 

 From the somewhat distant resemblance presented by the 



