Sept. 1, 1870.] 



HARDWICKE'S SCIENCE-GOSSIP. 



207 



In the same beds as these ripple-marks, sun- 

 cracks, rain-pittings, and worm-tracks, we have 

 innumerable remains of a small crustacean 

 (Palteopyge), which used to flit through the shallow 

 water in dense shoals. A pretty little zoophyte 

 (Oldhamid) lived in quiet, sheltered spots, Avhere it 

 luxuriated abundantly, its little branched stems 

 forming miniature forests along the old sea-bottom. 

 These lowly creatures are almost all I remember 

 of what is called the Lower Cambrian formation. 

 The upper portion, however, is much richer in 

 fossils ; and well do I remember when these now 

 petrified creatures enjoyed the pleasures of animal 

 life. Between the deposition of the strata of these 

 upper and lower formations there was a break in 

 the locality where I was born. Probably somewhere 

 else in the globe there will be found a formation 

 (possibly limestone) which was elaborated during 

 this provisional rest. Of that, however, I can only 

 conjecture. Concerning the animals which lived in 

 the Upper Cambrian seas, I can speak more posi- 

 tively. They were, first of all, far more abundant, 

 both in species and individuals. Thus the basement 

 rocks of this subdivision go by the name of Lingula 

 flags, from the vast quantities of the fossil of that 

 name occurring in them. The Lingula was a 

 mollusk occupying the lowest class among shell-fish, 

 that termed BracJiiopodous, or " arm-footed," from 

 the peculiar arrangement of the cilia. Strange 

 enough, this genus is still in existence, and you can 

 hardly tell the difference between the homy shells 

 of the living species and that which lived at this 

 early epoch. Talk about genealogy; no other family, 

 except that of the marine worms, can claim an anti- 

 quity so vast. Notwithstanding all the mutations 

 through which the surface of our old world has 

 passed — the upheaval of sea-bottoms into mountain- 

 heights, the depression of mountains into sea- 

 bottoms — this one genus of shell-fish has 

 triumphantly surmounted them all ! It is now, 

 I am told, fast passing into extinction, the final 

 lot to which so many genera of subsequent date 

 have succumbed. Among other animals which 

 lived at the time was a species of shrimp 

 {Hymenocaris) , whose remains may be met with in 

 the same rocks. Along this sea-bottom, in various 

 places, lived colonies of a kind of sea-lily, or rather, 

 of an animal halfway between these and the more 

 recent sea-urchins : these now go by the name of 

 Cystideans. Euruished with a short footstalk, which 

 served to anchor them to their selected habitats, 

 they flourished on the foraminifera which swarmed 

 in the waters of these primeval seas. 



Later on was introduced a crustacean afterwards 

 to become famous, both for its abundance and the 

 number of generic and specific forms it assumed. 

 This was the well-known Trilobite. Several genera, 

 and still more numerous species, were in existence, 

 and so fast did the newly introduced species breed, 



that they became the tyrants and scavengers of 

 these early seas. 



Most of my listeners are acquainted with their 

 trilobcd forms (whence their name), and have 

 admired the jointed coat of mail which protected 

 them, and, at the same time, gave them all the 

 necessary flexibility for movement. 



Out in the deeper water lived a peculiar kind of 

 mollusk, whose type is still living. This is termed 

 Theca, and its external protection consisted in a 

 thin, almost glassy case ; not so fragile, however, 

 but that it has been carefully fossilized. But in 

 gritty sandstones, or coarse slates, it is rare you will 

 find any remains of the old calcareons shells of the 

 various creatures I have named. Subsequent 

 changes, most of all the percolation of draining 

 water, have removed the limy material ; so that the 

 fossils found are principally as casts. Perhaps the 

 lime thus removed has, in many cases, served as a 

 natural cement to the sandy or clayey particles, so 

 that much of the hardness which now characterizes 

 these rocks was originally due to the limy sub- 

 stance of the Cambrian inhabitants. 



Towards the close of this remarkable period, other 

 forms of life appeared, the total number of genera and 

 species considerably increasing. Shell -fish of a higher 

 grade were introduced, until the highest type — the 

 Cephalopoda — was brought on the stage of existence 

 in the shape of Orthoceratites. These were allied 

 to the living nautilus, only they had straight cham- 

 bered shells, instead of coiled ones. Their arms, 

 something like those of a cuttle-fish, extended out 

 of the last, or body-chamber ; and on these, with 

 shell inverted like a spire, the creature would occa- 

 sionally crawl over the muddy sea-bottom where I 

 was slowly forming. Belly-footed mollusca {Gas- 

 teropoda), in the shape of a genus which has been 

 extinct since the time of the coal formation, crawled 

 about as Bellerophon, its gracefully coiled shell 

 being as beautiful as any of its recent represen- 

 tatives. Thus did the Cambrian period come to a 

 close. 



Of course my listeners cannot expect one poor 

 memory accurately to remember all the types of 

 life then existing ! Suffice it to say that, compared 

 with those of subsequent periods, they were few 

 and of a much lowlier kind : numerical abundance 

 of individuals made up for poverty of genera and 

 species. It was the dawn of life— when organisms 

 were in the cradle. Betwixt this and chaos was a 

 great gulf fixed. The first outlines of that grand 

 scheme which should ultimately link inorganic 

 matter with spirit, were then rudely sketched. 

 Time was ordained for the sole purpose of filling 

 them up, and, when the object is completed, time 

 shall be no longer ! Even since this distant period, 

 life has progressed until it has reached its physio- 

 logical maximum in man. But in him, I am told, 

 appear the germs of a new spiritual life, whose de- 



