4i8 



NATURE 



[Mar. 28, 1872 



Snelus, Jones, and Lester — reported the system as a 

 complete success, and well suited for the treatment 

 of the iron of this country, an announcement which was 

 received with the greatest interest ; and steps were imme- 

 diately taken to erect similar appliances in England, sothat 

 already in the month of February, one of Mr. Danks's 

 furnaces was at work with results which fully corroborated 

 the report of the commissioners, and left no doubt but 

 that the invention must entirely revolutionise this branch 

 of the iron manufacture, doing away with the severe, and 

 it might almost be called degrading, labour of manual 

 puddling altogether, and in other respects producing 

 wrought-ironof a more certain and superior quality to the 

 product obtained from the same pig-iron by the old 

 system. 



It is almost impossible to over-estimate the direct and 

 indirect benefits which must accrue to that greatest of all 

 metallic industries, the iron manufacture ; and as it might 

 have been years before this invention had asserted itself 

 had it not been taken up so energetically by the Iron and 

 Steel Institute, this may be mentioned as a striking in- 

 stance of the important results which may be expected 

 from the labours of such a society. 



NICHOLSON ON THE GRAPTOLITES 



Monograph of the British Graptolitidce. By H. A. 

 Nicholson, M.D., &c. (Edinburgh : Blackwood and 

 Sons.) 



IT is with no small degree of satisfaction that we 

 welcome the appearance of the first part of Dr. H. 

 A. Nicholson's Monograph of the British Graptohtes, 

 the first English essay attempting a clear digest or 

 history of this very difficult and perplexing group of 

 fossils. Dr. Nicholson has, however, for years lived in 

 those regions whose rock masses, life contents, and struc- 

 ture were long since elucidated and rendered classical and 

 famous by the researches of Sedgwick ip 184S; and 

 where these organisms are most abundantly distributed. 

 Patient investigation of the great stores of entombed 

 materials at his command, combined with requisite know- 

 ledge of zoolog)', has favoured the author in the prepara- 

 tion of this valuable contribution to our hitherto limited 

 knowledge of these extinct forms of life. 



Much has been written upon the Graptolitida;, but in a 

 disjointed manner, by numerous writers since 1727 ; but 

 Linna:us, in his " Skanska Resa" in 176S, first applied 

 the name " graptolithus " to some or certain allied forms 

 occurring in the Scandinavian rocks. Much controversy 

 has been carried on about this original scalariform type 

 of graptolite ; some writers believing it to have been a 

 monoprionidian, others a diprionidian genus. It signifies 

 little now save as matter of history. Since then eighteen 

 genera and ninety species have been established and recog- 

 nised in Britain alone, and these have been mostly obtained 

 from rocks of Lower Silurian age. Seven species out of 

 the ninety are only known in the Upper Silurian rocks, and 

 four of these are peculiar to that horizon, or do not range 

 lower. The authenticity then of the character of the one 

 and disputed Linnsan form, will do little more after 

 all than add to the literature of the group. This original 

 figure is sufficient to show us that it was a graptolite in 



our acceptation of the genus, and doubtless the form 

 looked upon and drawn by the illustrious Swede was one 

 of millions contained in the black and slaty rocks over 

 which he travelled ; a form, with many others since 

 discovered, and now known to all students of those 

 Silurian rocks which belt the earth from Canada to 

 Britain, Scandinavia, Saxony, and Bohemia, and on to 

 Australia. The historical notice of the Graptolitidje 

 occupies seventeen pages, and forms a compilation of 

 the bibliography of the group, for which all students will 

 gladly thank the author, from 1 82 1-2, when W.ihlenberg 

 and Schlotheim advocated their alliance to the Cephalo- 

 poda, to Hopkinson's last paper in 1871 [describing the 

 reproductive capsules). We have, in fact, a well-digested 

 chronological history, enumerating about eighty notices, 

 and embracing the labour of thirty-five authors. 



To study and examine the graptolites iu situ, or as 

 they occur in the black paper like flaggy shales of the 

 Arenig, Llandeilo, and Caradoc beds, to which they are 

 chiefly confined in Wales, Westmoreland, Scotland, and 

 Ireland, is no small pleasure ; but after their strati- 

 graphical position or succession in time is definitely 

 settled in any area to the satisfaction of the physical geo- 

 logist or stratigraphist, the question of their zoological 

 affinities, or the position they hold in the animal kingdom 

 with relation to modern and existing types becomes one 

 of high importance and value, yet one even now not 

 satisfactorily determined or established. Were they free 

 swimming or floating bodies, in the old Silurian slms, or 

 were they attached like the hydroid Sertularidie of i. dern 

 shores and time ? These questions are dealt with by the 

 author under two heads : first, their mode of existence, 

 and secondly, their systematic position and affinities. To 

 our mind the modes of existence of the Graptolitida 

 have little weight in classification ; a knowledge of their 

 intimate structure alone must be the basis of their 

 zoological position in the animal kingdom. 



It was natural that the older writers should have referred 

 this extinct group to many divisions which themselves were 

 not then really understood ; and they have been placed 

 in no less than six divisions of the animal kingdom. 



Modern systematists, however, have referred them to 

 three groups — the Hydrozoa, Polyzoa, and Actinozoa. In 

 1839 Sir R. Murchison, in his Silurian System, placed 

 them with the Actinozoa, assigning their position to the 

 Pennatulida;, and related to the Virgularia of the northern 

 seas. No real analogy however exists between the 

 tubular chitonous fibre of the graptolites, and the cal- 

 careous or sclerobasic rod of Virgularia, whose c;ijnosarc 

 secretes no external envelope, and where the polypes are 

 not contained in, or protected by, special chitonous thecae. 

 All research also tends to show that the graptolites were 

 free bodies and perhaps oceanic ; the structure and con- 

 dition of the radicle or initial point is conclusive on this 

 point. With respect to their development we as yet know 

 little ; but the fact that, as in other Hydrozoa, the repro- 

 ductive organs were outwardly developed processes of the 

 body wall, strongly allies them to the Hydrozoa. Hopkin- 

 son has of late added much to our knowledge of the 

 external reproductive sacs or gonotheca; of Diplograpsus. 



To Colonel Pollock is undoubtedly due the suggestion 

 of their sertularian affinities through Sertularia and Plumu 

 laria, but they certainly are not their fossil representatives. 



