HISTORY OF RESEARCH. xlv 



The remarkable similarity between the graptolitic fauna of Australia, America, 

 and that of the Northern Hemisphere appears to have greatly astonished him ; 

 and he lays especial stress on the " extraordinary fact of the specific identity 

 of this marine fauna over the whole world during the most ancient Palasozoic 

 periods." 



A paper on the Graptolites of Ireland was published in 



, .. ' ,, ,, 1861 by Baily. It is mainly stratigraphical in its bearing, 

 "Graptolites of Meal h, J / J . . 



etc " ' G-eol Soc of but the various Graptolite species mentioned are briefly 



Dublin.' described and figured. 



Didymog. Murchisoni is recorded from Bellewstown, co. Meath ; and he 

 erroneously asserted that with this form were associated Gr. Sedgwiclcii and Gr. 

 Nilssoni. The species (1) Diplog.pristis, (2) var. scalariformis, (3) D. mucronatus, 

 (4) Gr. gracilis, and (5) Oladog. Forchammeri are recorded and figured by him 

 from "beds of Llandeilo age" in county Clare. As regards the first two of these 

 species, he points out that the specific names given by him are merely provisional. 

 His D. pristis var. scalariformis appears to be a Climacograptus. The example 

 shown on fig. 2 J>, is probably Olimacog. tubuliferus, Lapw. His Diplog. mucronatus 

 is the D.bimucronaius, Nich. The structure of the cells in his Cladog. Forchammeri 

 are well represented. 



From co. Tipperary he records Gr. priodon and a new species, Gr. hamatus 

 (Cyrtograptus) . 



Referring to the range of the Craptolites in general, Baily concludes that " all 

 the double forms are confined to the Lower Silurian division, being most abundant 

 in the lowest series of beds, the equivalents of the Llandeilo Flags ; one species 

 only, the Gr. priodon, a single form, ranging through the series." 



In 1863 Salter, in an appendix to Harkness' paper on 



g n j ter " The Skiddaw Slate Series," recorded and figured several 



"Note on Skiddaw species of Graptolites. They include the (1) Phyllog. angusti- 



Slate Fossils," 'Quart, folius of Hall, and two species of Tetragrapsus. One of these 



Journ. Geol. Soc.,' - g c ] ear iy (2) T. serra, and the other a presumed new species 



named by Salter (3) Gr. crucialis. This last, however, is 



identical with the T. quadribrachiatus of Hall. 



Two new species of Dichograpsus are named, (4) D. aranea (D. octobrachiahis) 

 and (5) D. Sedgwickii, and a form is figured with a disc. A figured fragment 

 (fig. 12) assigned by Salter to Dichograpsus is really an example of Bryograptus 

 Kjerulfi. Four species of Didymograpsus are figured : — (6) D. caduceus, (7) l>. 

 geminus, (8) D. v. fractus, and (9) />. hirundo. The last two are new forms. 



Salter agrees with Huxley's suggestion that the disc in Dichograpsus is analogous 

 to the basal plate of Defrancia, and he regards it as of great systematic importance. 

 He accepts Hall's genera Dendrograptus and Dictyonema, and points out the strong 



9 



