182 



HARDWICKE'S SCIENCE-GOSSIP. 



shown that they were fixed or rooted, like the 

 " Sea-firs," and therefore very similar to them. 



The reader will perceive the nature of the discus- 

 sion, which has terminated in so many opinions as to 

 the true natural-history relations of these interest- 

 ing fossils, and will undoubtedly arrive at the con- 

 -clusion that their nearest living allies are the 

 *' Corallines," or "Sea-firs" (Serttilaria?), although 

 they had strong affinities with a group of animals 

 oven lower in organization than the latter, namely, 

 the Rhizopods. 



Carruthers has published a " Revision " of these 

 fossils, in which the leading types are grouped as 

 follows, beginning with Rastrites: — In this genus 

 the polypary consists of a simple, slender, hair-like 

 lube, from which project a series of detached cups 

 {hydrotltecai) . 2. The old genus, which was named 

 by Linnaeus Graptolitlms. This has given the popu- 

 lar name to the entire group. In it the polypary is 

 simple, and the cups are so thickly grouped along 

 one side that they are all in contact with one an- 

 other (fig. 121). 3. The genus named Cyrtograpsus 

 by Mr. Carruthers, in which the polypary grows in 

 one direction, and gives off simple or compound 

 branches at intervals. 1. The genus Didymograpsus ; 

 in this we have, as it were, a double graptolite, of 

 a forked shape, with the cups arranged within the 

 fork (fig. 120). The geometrical forms assumed by 

 the coupled branches, or polyparies, are various in 

 different species. 5. Dichograpsus ; a branched, and 

 therefore possibly a rooted, genus of Graptolites. 

 <3. Cladograpsus ; another compound, or brauched, 

 sessile genus. In this the branches often give rise 

 to other irregular branches, the first part of the 

 name signifying a branch. 7. De/idrograpsus is an- 

 other " tree-shaped," and therefore compound- 

 rooted, sertularian-like graptolite, with a thick 

 main stem. 8. Diphgrapsas (fig. 122) ; in this the 

 cups are arranged on each side the axis, so as 

 to present the appearance of two simple Grapto- 

 lites being placed back to back. 9. Climatograp- 

 sits; a genus so named by Professor Hall, of Ame- 

 rica, in which the polypary has a double series 

 of cells hollowed out of the outer covering. 10. 

 Lastly, we have Dicra/iograps/ts ; having double rows 

 of cells in the lower part, with branches possessed 

 of only single rows of cups or cells in the lower part, 

 with only single rows of cells in the upper. 



In the Arenig rocks of Ramsey Island, the 

 branched forms seem to be tolerably abundant, and 

 Mr. Hopkinsou has shown that these have a nearer 

 relation to the species of Graptolites from Quebec 

 than any other found in Great Britain. Many of 

 the species are branched. The branched or double 

 form of Graptolite seems to be peculiar to the 

 Lower Silurian rocks ; whilst the fewer species met 

 with in the upper strata are usually of a simpler 

 character. Some compound forms seem to have 

 attained great length ; thus, a species of Ple/iro- 



grapsus has been traced, over 3 feet long, although 

 even this does not seem to have been the full size. 

 The Skiddaw slates were formerly believed to 

 form the lowest horizon where the Graptolites were 

 met with, but Mr. llopkinson's discovery of them, 

 lower down in the Arenig rocks, not only extends 

 their antiquity, but, owing to the similarity of type 

 between the Arenig species and those from Quebec, 

 suggests that their geographical distribution into 

 colonies occurred later on through the subsequent 

 geological changes which took place. 



Doubtless, one of the very best hunting-grounds 

 for British Graptolites is Dumfriesshire. That county 

 is largely underlaid by Lower Silurian rocks, de- 

 posited along the floors of ancient seas, as so much 

 marine mud. Little did the numerous Graptolites 

 know that they were forming no insignificant 

 part in laying down the foundations of the " Land 

 of brown heath and shaggy wood "; a land to be 

 uplifted for ages above sea-levels ; on which the 

 storms and atmospherical action of thousands of 

 centuries should be expended, until its surface had 

 become carved into hill and dale, lake and valley, 

 gorge and glen, over all of which genius should throw 

 the halo of ever-enduring romance ! This wild land 

 teems with as many relics of the semi-barbarous 

 mediaeval humau period as it does with primeval 

 fossils. The heroes, not only of Scott, but of many 

 an unchronicled feud and deed of daring, have 

 sought shelter in glens and linns where the black 

 shales through which these had been cut were 

 crowded with pyritized Graptolites. At Lockerbie, 

 for instauce, — famous for its "Lockerbie lick," 

 in reference to the part it took in the old Border 

 feuds and forays, — the black shales of the Lower 

 Silurian rocks abound with these interesting fossils. 

 Owing to the sottish nature of the shales, and the 

 way in which they allow water to ooze through 

 their joints, many of the glens in them are well- 

 wooded, and rich in flowering plauts. In the shales 

 at Lockerbie the pretty double Graptolite Diplo- 

 grapsus lotus, as well as D. pridis aud D. recta/igu- 

 laris, are very abundant, the latter species particu- 

 larly so. 



The neighbourhood of Moffat, also, is good 

 grouud for Graptolites. Many new species have 

 been recently described from this district. At Hart 

 Pell we have such forms as Biplograpsus pristis, D. 

 tertiusculus, 1). mucronatus, Bidymograpsus Jlac- 

 cidus, D. sextans, and many other commoner forms. 

 In this well-wooded region, rendered classic by 

 Burns and Hogg, the geological student cannot 

 cast his eyes in any direction without recognizing 

 some kind of geological agency or another. All the 

 hills hereabout show traces of glacier action, in 

 rounding strise, or otherwise. Burns's " Craigie- 

 burn Wood" lies itself in the heart of the grapto- 

 litic shales, whilst the student of Scott's " Bed- 

 gauntlet" will hardly fail to recognize the graphic 



