PALAEONTOLOGY. 27 1 



destruction of ancient and the manifestation of recent organ- 

 isms. A few of these older structures have remained in tln> 

 midst of more recent species. Owing to the limited nature of 

 our knowledge of existence, and from the figurative terms by 

 which we seek to hide our ignorance, we apply the appellation 

 recent structure to the historical phenomena of transition man- 

 ifested in the organisms as well as in the forms of primitive 

 seas and of elevated lands. In some cases these organized 

 structures have been preserved perfect in the minutest details 

 of tissues, integument, and articulated parts, while in others, 

 the animal, passing over soft argillaceous mud, has left noth- 

 ing but the traces of its course,* or the remains of its undi- 

 gested food, as in the coprolites.f In the lower Jura forma- 

 tions (the lias of Lyme Regis), the ink bag of the sepia has 

 been so wonderfully preserved, that the material, which myr- 



* [In certain localities of the new red sandstone, in the Valley of the 

 Connecticut, numerous tridactyl markings have been occasionally ob- 

 served on the surface of the slabs of stone when split asunder, in like 

 manner as the ripple-marks appear on the successive layers of sandstone 

 in Tilgate Forest. Some remarkably distinct impressions of this kind, 

 at Turner's Falls ( Massachusetts \ happening to attract the attention of 

 Dr. James Deane, of Greenfield, that sagacious observer was struck 

 with their resemblance to the foot-marks left on the mud-banks of the 

 adjacent river by the aquatic birds which had recently frequented the 

 spot. The specimens collected were submitted to Professor G. Hitch- 

 cock, who followed up the inquiry with a zeal and success that have 

 led to the most interesting results. No reasonable doubt now exists 

 that the imprints in question have been produced by the tracks of bi- 

 peds impressed on the stone when in a soft state. The announcement 

 of this extraordinary phenomenon was first made by Professor Hitch- 

 cock, in the American Journal of Science (January, 1836), and that 

 eminent geologist has since published full descriptions of the different 

 species of imprints which he has detected, in his splendid work on tho 

 geology of Massachusetts. Mantell's Medals of Creation, vol. ii., p. 810. 

 In the work of Dr. Mantell above referred to, there is, in vol. ii., p. 815, 

 an admirable diagram of a slab from Turner's Falls, covered with nu- 

 merous foot-marks of birds, indicating the track of ten or twelve indi- 

 viduals of different sizes. } Tr. 



t [From the examination of the fossils spoken of by geologists under 

 the name of Coprolile*, it is easy to determine the nature of the food of 

 the animals, and some other points; and when, as happened occasion- 

 ally, the animal was killed while the process of digestion was going on, 

 the stomach and intestines being partly filled with half-digested food, 

 and exhibiting the coprolites actually in titv, we can make out with 

 certainty not only the true nature of the food, but the proportionate size 

 of the stomach, and the length and nature of the intestinal canal. With- 

 in the cavity of tho rib of an extinct animal, the palaeontologist thus 

 finds recorded, in indelible characters, some of those hieroglyphics upon 

 which he founds his history. The Ancient World, by D. T. Ansled, 

 1847, p. 173.] Tr. 



