xlii 



BRITISH GRAPTOLITES. 



Carruthers' first paper on the Graptolites appeared in 

 1858 in the ' Transactions of the Royal Physical Society 

 of Edinburgh.' It was, however, republished in 1859 in 

 the ' Annals and Magazine of Natural History.' It contains 

 a description of three new species from the Silurian shales 

 of Dumfriesshire, viz. (1) Cladograpsus (Pleurograptus) 

 linearis, (2) Diplograpsus (Cryptograptus) tricornis, and 

 (8) Didymograpsus (Dicellograptus) Moffatensis. Carruthers 

 suggests the generic title of Cladograpsus for forms " having 

 two main stems each supporting the cells on their upper sides," and with 

 " branches given off at irregular distances." This name, as we have already 

 seen, had been employed by Geinitz and Emmons for forms generically distinct 

 from those for which it Avas proposed by Carruthers. 

 1859. 



1858-9. 



Carruthers, 



" On the Graptolites 



from the Silurian 

 Shales of Dumfries- 

 shire, with a Deserip- 



tion of three new 



Species," 'Ann. Mag. 



Nat, Hist,,' ser. 3, 



vol. iii. 



Giebel, 



"Die Silurische Fauna 



cles TJnterharzes," 



1 Zeit. f iir die Gresammte. 



Natur. Wiss,' vol. xi. 



Iii the year 1851) also Giebel recorded Monog. Sagittarius 

 from the Silurian beds of the Lower Harz. 



1859. 

 Hall, 



Supplement to vol. i, 



Palaeontology of New 



York,' vol. iii. 



In 1859, in a supplement to vol. i of his ' Palaeontology of 

 New York ' (which supplement was, however, actually pub- 

 lished simultaneously with vol. iii), the preceding " Notes " 

 were reproduced by Hall, and some additional new forms from 

 the Hudson River group were figured and described. 

 These include (1) Gfr. multifasciatus (a many branched form, Amphigraptus) ; 

 (2) Gr. divaricatus (Dicellograptus); (3) Gr. gracilis (Coenograptus, Hall); (4) (Jr. 

 marcidus (Gryptograptas); (5) Gh\ Whitfieldi, (6) Gr. angustifolius (Diplograptus); 

 (7) Gr. spinulosus (Glossograptus); (8) Retiograptus Geinitzianus (Clathrograptus) ; 

 (9) Thamnograptus typus and (10) T. capillaris, (11) io/N/W/r.vBarrandi {? Thamno- 

 graptus). 



As regards the points of structure brought out in the examination and descrip- 

 tion of these species, Hall remarks that in Thamnograptus the cellules are at present 

 unknown. In Gr. divaricatus he calls attention to a row of small nodes placed 

 obliquely to the direction of the axis. He figures a large specimen of Gr. gracilis, 

 and 1 races the stages in development from the earliest, in which there are no lateral 

 branches, through the form now referred to Nenuuj. [Goenog.) surcularis, up to 

 I lie large and typical form. He notices the radicle or axillary bar from which the 

 main stipes diverge, and writes that "it is barely possible that the apparent 

 central radicle may We the remains of two other stipes, corresponding to the 

 two usually preserved." lie argues that it is " still possible that these small 

 In furcate fronds are hut the separated offshoots from a rhizoma, which extended 





