Mar. 28, 1872] 



NATURE 



419 



The author wisely " regards them as a special group of 

 Hydrozoa " unrepresented by any living forms, and forms 

 them into a distinct sub-class. 



Chapter II. is devoted to the fonn and mode of 

 reproduction. This, we think, would have been better 

 placed after the chapter on their special morphology, or 

 prior to Chapter VIII., which is devoted to their geological 

 distribution. We are prepared to admit, however, that 

 much error has arisen from our want of clearly under- 

 standing their true history and the mode of their preser- 

 vation in rocks of such varied physical texture and chem- 

 ical condition. 



Chapters III. and IV. are devoted to the general and 

 special morphology of the graptolites ; typical forms being 

 selected in Chapter III., in which the main anatomical 

 features and aspects are recognisable. For this purpose 

 the author has selected the well-known forms of G. Sagit- 

 tarius, G. coloniis, and Cliuiacograpsus feretiusculns, and 

 devotes fifteen figures to the elucidation of the monopri- 

 onidian and diprionidian type of structure. 



Chapter IV. embraces thirteen pages and thirty-five 

 figures devoted to the special morphology of the grapto- 

 lites. We regard this chapter as a condensed history or 

 digest of the labours of European, American, and British 

 graptolithologists. The views and labours of Hall in 

 Canada, Geinitz, Nilsson, and Barrande in Europe, Salter, 

 Carruthers, M'Coy, Hopkinson, Harkness, &c., and the 

 author in Britain, are embodied under the nature of the 

 solid axis, common canal, cccnosarc, cellules, and ornamen.- 

 tation of the polypary. 



Space forbids us to do more than notice that in Chapter 

 V. twelve pages and twenty-two figures are occupied by 

 the consideration of chief and special portions of the 

 graptolites, viz. the "radicle or initial point of Hall," and 

 the basal process, the funicle, or non-celluliferous connect- 

 ing process, largely developed in the Dichograpsi, and the 

 central disc of the Tetragrapsi. Whether these corneous 

 bodies find their analogue in the float of certain oceanic 

 Hydrozoa has yet to be determined. 



The chapter upon reproduction and development con- 

 tains much important matter. The evidence of repro- 

 ductive organs, however, amongst a group so obscurely 

 preserved as the graptolites must be studied with much 

 care, and deductions received with much caution, but 

 since Hall, in 1858, first drew attention to what he 

 believed were ovarian capsules, Mr. Hopkinson in iS/r 

 confirmed the discovery and description of pyriform gono- 

 thecffi or ovarian capsules vcvDiplograpsus pristis. 



Nicholson had, in 1866, noticed bodies which he 

 believed to be, and referred to, reproductive bodies, and 

 named them grapto-gonophores. He, however, had doubts 

 as to their analogy. Mr. Carruthers differed from the 

 deductions of Nicholson, maintaining that these bodies 

 were accidental, or did not belong to the graptolites, 

 although associated or in juxtaposition with them. 



Mr. Carruthers first drew attention to and noticed the 

 existence of young forms of graptolites ; but Prof. Hall 

 appears to have been the first to make accurate obser- 

 vations upon their development (Grap. of Quebec group, 

 PI. B, p. 12 — 19). We, however, as yet know little about 

 this obscure question or point in their history. 



The chapter upon the systematic or zoological position 

 of the graptolites is a valuable one, the author taking 



and adopting what we believe to be the right view, 

 placing the/ii in the hydrozoa. This is the first and invari- 

 able question of the systematist ; the naturalist shirks the 

 question and waits. 



It is quite impossible within the limits at our command 

 to discuss the interesting problem of the geological dis- 

 tribution of the graptolites. Although strictly Silurian as 

 regards age, and only occurring in rocks of that period, 

 yet their assignment to the special area which gave birth 

 to them, and from whence they became distributed in 

 space, is a problem yet to be worked out. We believe 

 this has been elsewhere attempted by the author. That 

 the Quebec genera and many species agree in the 

 main with the so-called Arenig or Skiddaw sfete forms in 

 Britain is certain, and this is a fact of much interest as 

 a question of distribution. At present we know of no 

 species in the Tremadoc beds, omitting Dictyonema of 

 doubtful affinity ; and the statement that the lower 

 Llandeilo flags of Wales are the precise equivalents of 

 the Skiddaw slate of Westmoreland needs confirmation ; 

 neither should we hastily accept the generalisation that 

 the Potsdam group in America is upon the horizon of 

 the Skiddaw series, but rather perhaps refer the Quebec 

 and Chazy series to the Arenig or Skiddaw beds of the 

 lake country, where, or in the Llandeilo area in Wales, the 

 graptolites perhaps came first into existence, unless to 

 Canada we refer theirbirth-place. Homotaxically,however, 

 we require more data. Nine out of fifteen genera are 

 common to Britain and Canada ; and this though the Skid- 

 daw slates of Westmoreland, indeed the Skiddaw and 

 Llandeilo rocks and their equivalents, are the graptolitic 

 beds throughout Europe if not the world. The old 

 generalisation as to the diprionidian species occurring in 

 the Upper Silurian is confirmed and borne out by the 

 researches of Nicholson : the unsatisfactory genus Retio- 

 lipes alone being found. The sea which deposited the 

 Caradoc rocks saw the last of the compound species, and 

 the physical nonconformity was also a zoological one, 

 especially in hydrozooid life. Indeed only 140 species of 

 all groups of 1,450 known Silurian species, or 10 per 

 cent., are common to rocks of Lower Silurian and Upper 

 Silurian time. 



Chapter IX. deals with the generic characters of the 

 radiculate group, omitting those of doubtful affinity ; the 

 author followsthe sectional grouping of Barrande, adopting 

 monoprionidian and diprionidian, &c., as modified by 

 Hopkinson. 



We look forward with much interest to the part con- 

 taining full and detailed descriptions of the species. The 

 splendid volume by Prof Hall and Sir William Logan 

 upon the Canadian species (Report of Progress of the 

 Geological Survey of Canada, 1857, and figured descriptions 

 of Canadian organic remains Decade 2, Grap. of Quebec 

 group) «e Hope to see equalled if not surpassed by the 

 author of the present valuable memoir. R. E. 



OUR BOOK SHELF 



Observations upon the Climate of Uckfield. A Meteoro- 

 logical Record for the district from 1843 t° 1870, &c. 

 By C. Leeson Prince, M.R.C.S., F.R.A.S. (London : 

 Churchill, 1871.) 

 We opened this work expecting to find in it a mere record 

 of the barometric and thermometric observations taken 



