AMPHIBIA. 



AMPHIBIA. 



1M 



secondary plate* whick are given off near the centre of the tooth also 

 divide into two before they terminate. They partake of all the 

 un I ilations which ch tractor!** the inflected foldii of the cement 



"Tha central pulp-cavity ii reduced to a line, about the upper 

 thir.l of the tooth ; but liwureo radiate from it, corresponding in 

 number with the radiating plates of the dentine. One of these 

 nature* U continued along the middle of each plate, dividing where 

 it divide*, and penetrating each bifurcation and process ; the main 

 fiaiurm extend to within a line or half a line of the periphery of the 

 tooth ; the termination* of these, u well ai the fissure* of the lateral 

 processes, luddenly dilating into ubcircular, oval, or pyriform spaces. 

 Ail theae space* constitute centre* f radiation of the fine calcigerous 

 tube*, which, with their waiting clear substance, constitute the dentine. 

 The number of these caloigeren* tabes, which are the centre* of minor 

 ramification*, defies all calculation. Their diameter U the y.-i^th of 

 a line, with interspace* equal to 7 diameter* of their cavities." 



By the permission of lrofe.or Owen we are enabled to give a 

 section of this highly complicated tooth, from his elaborate ' Odonto- 

 prsphy' (pL 64, A.), in which the subject ia treated with minute 

 detail ( part ii, p. 203, Ac.). 



Tnuuvene Section of Tooth of Lahyrinthtdon JSgeri (Owen) ; lliatndnn- 

 taunu JSfiri (Meyer) ; nstanl Biie, and a segment magnified, a, pulp-cavity, 

 from which the processes of pulp and dentine radiate ; I, cement. 



In connection with this subject we may call the reader's attention 

 to some fact* of considerable interest, which have lately been studied 

 with much care and success, and have become of such importance as 

 to constitute a distinct branch of inquiry under the name of 

 Ichmtlogy ( lx'<", footstep, and X^yoi, a discourse). 



This department of geological investigation is conversant with the 

 phenomena of footsteps impressed by animals on the strata of the 

 earth. 



In 1828 Mr. Duncan's account of tracks and footmarks of animals 

 impressed on sandstone in the quarry of Corn-Cockle Muir, Dumfries- 

 shire, appeared in the 'Transactions of the Royal Society of 

 Edinburgh.' Dr. Buckland caused a living Emyi and Tatudo Graca 

 to walk on soft sand, clay, and -paste or unbaked pie-crust. He found 

 the correspondence of the footsteps of the latter with the fossil 

 footsteps sufficiently close, allowing for difference of species, to render 

 it highly probable that the fossil footsteps were impressed by Tat tub 

 i, .,,,, 



In Saxony, at the village of Hesaberg, near Hildburghausen, fossa 

 footstep* were, a few year* ago, discovered in several quarries of gray 

 Quartzose Sandstone alternating with, beds of Red-Sandstone, nearly 

 of the age of the Red-Sandstone of Corn -Cockle Muir. Dr. Hohnbaum 

 and Professor Kaup state that these impressions of feet are partly 

 concave and partly in relief ; the depressions are described as being 

 upon the upper surfaces of the Sandstone slabs, but the footmarks in 

 relief are only upon the lower surfaces, and cover the depressions. 

 In short, the footmarks in relief are natural casts formed in the 

 subjacent footsteps as in moulds. On one slab, 6 feet long by 5 feet 

 wide, many footsteps of more than one nniml and of various sizes 

 occur. The larger impressions, which seem to be those of the hind- 

 foot, are generally 8 inches in length and 5 in width, and one was 

 12 inches long. 



The name of Chirotherium was proposed by Professor Kaup as the 

 provisional name for the great unknown animal that impressed' the 

 larger footsteps, from a supposed resemblance in the marks of both 

 the fore- and hind-feet to the impress made by a human hand ; and he 

 thought that they might have been derived from some quadruped 

 Uiedto the Mampialia. l)r. Sicklcr, in a letter to Blumenbach 

 ( 1834 ), gave a further account of these footsteps. Fragments of 

 bones were found in the quarries where the footsteps bad been 

 imprested, but those fragments were destroyed. 



The existence of footprints of thi* kind soon became more exten- 



sively known. In hi* address to the Oeological Society, in 1840, Dr. 

 Buckland says : " Further discoveries of the footsteps of (.'/ 

 rium and five or six smaller reptile* in the New Red-Sandstone of 

 Cheshire, Warwickshire, and Salop, have been brought before us by 

 Sir P. Egerton, Mr. J. Taylor, jun, Mr. .Strickland, and Dr. Ward. 

 Mr. Cunningham, in a aoquel to hi* paper on the footmark* at Storeton, 

 ha* described impression* on the *ame slabs with them, derived from 

 drops of rain that fell U|HHI thin lumimn of clay interposed between 

 the bed* of sand. The clay impressed with these prints of rain-drops 

 acted as a mould, which transferred the form of every drop to the 

 lower surface of the next bed of sand deposited upon it, so that 

 entire surfaces of several strata in the same quarry are resix 

 covered with moulds and cants of drop* of rain that fell whilst the 

 strata were in process of formation. On the surface of one stratum 

 at Storeton, impressed with large footmarks of a CkintJirrium, the 

 depth of the hole* formed by the rain-drops on different parts of the 

 same footstep has varied with the unequal amount vf pressure on 

 the clay and sand, by the salient cushions and retiring hollows of 

 the creature'* foot ; and from the constancy of this phenomenon 

 upon an entire series of footmarks in a long continuous track, we 

 know that this rain fell after the animal had passed. The equable 

 size of the casts of large drops that cover the entire surface of the 

 slab, except in the parts impressed by the cushions of the feet, 

 record the falling of a shower of heavy drops on the day in w lii.-li 

 this huge animal had marched along the ancient strand. Hemispherical 

 impressions of small drops, upon another stratum, show it to have 

 been exposed to only a sprinkling of gentle rain that fell at a ni 

 of calm. In one small slab of Sew Red-Sandstone found by Dr 

 near Shrewsbury, we have a combination of proofs a* to meteoric, 

 hydrostatic, and locomotive phenomena, which occurred at a time 

 incalculably remote, in the atmosphere, the water, and the movements 

 of animals; and from which we infer, with the certainty of cumulative 

 circumstantial evidence, the direction of the wind, the depth and 

 course of the water, and the quarter towards which the animals were 

 passing : the latter is indicated by the direction of the footsteps 

 which form their tracks ; the size and curvatures of the ripple-marks 

 on the sand, now converted to sandstone, show the depth and 

 direction of the current ; the oblique impressions of the rain-drops 

 register the point from which the wind was blowing at sr about the 

 time when the animals were passing." 



Seon after this address was delivered. Professor Owen proved the 

 existence of a gigantic Batrachian at the period when the New Red- 

 Sandstone was formed, and described three species of Labyrinthodon. 

 He concluded that these creatures produced the foot-prints that had 

 been observed, and maintained the following positions : 



1st Proof from the skeleton that LabyrinthoAon had hind extre- 

 mities much larger than the anterior extremities. 



2nd. That the foot-prints of Chirotherivm are at least as mch like 

 those of certain Toads as those of any other animals. 



3rd. That the size f the known species of Labyrintkoton corre- 

 sponds with the size of the foot-prints of the different species of 

 Ckirolheriitm ; e.g. Labyrinthodon Jtiferi, with the foot-print of 

 Chirotherium Herculet (Egerton); 'Lakyrintkodon pafli ygnathut, with 

 the foot-marks of the common Ckirollierium ; and Labyrintkodon 

 ItptoynaHiu with the impressions of the smaller Batrachian figured 

 in the memoir by Sir Roderick Murchison and Mr. Strickland. 



4th. Lalyrintkodon occurs in the New Red-Sandstone strata to 

 which Chirotherian impressions are peculiar. And 



Lastly, no remains of animals that could have left such impressions 

 as those of the Chirotherium have been found in these strata, except 

 the remains of the Labyrinthodon. 



Fora and hind-foot of the tame. 



It is true that the structure of the foot is still wanting, and that a 

 more connected and complete skeleton is required for demonstration.,- 

 loit the circumstantial evidence above stated is strong enough U> 



