xcii BRITISH GRAPTOLITES. 



embraces three formations — the Glenkiln, Hartfell, and Birkhill— answering 

 respectively to the Upper Llandeilo, Bala, and Lower Llandovery formations of 

 Southern Britain and is separable into at least eleven Grraptolitic zones. 



An attempt to study the minute structure of Graptolites 

 by means of dissolving: away the calcareous matrix, and 



(in iiiliri, . ' ^ 



"Einige Bemerkun^en isolating the Graptolite, was made in 1878 by Giimbel. 



iiber Grraptolithen," ^ ne experiments were made with specimens of M. jpriodon, 



'Neues Jalirb.,' 1878. and accurate drawings of some of the cells, both in relief and 

 in section, are given in his paper. Giimbel notices par- 

 ticularly the thickening of the cell-wall in three places— (1) at its proximal end, 

 (2) at the point of j miction with the cell- wall next above, and (3) at the edge of 

 the aperture. 



As a result of his tests he believes that the skeleton is formed of a "structure- 

 less, membranous substance, consisting of several thin layers," like the chitinous 

 skeleton of the Sertularia. 



He records the existence of two distinct Graptolite horizons in the Fichtelge- 

 birge. He notes the discovery of Cyrtograptus ? Murchisoni and Pleurograptus cfr. 

 linearis, from the Upper Graptolite shales. 



1878. 



Richter, 

 " Notize iiber die 

 G-raptoliten d. H 



Die altesten Devon. 

 Ablagerungen des 



Harzes," ' AMiamll. 



Giimbel's paper was briefly referred to and criticised by 

 Richter in another number of the ' Nones Jahrbuch ' for the 

 Giimbels," same year, and his conclusions are in the main accepted. 



Neues Jalirb.' 



1878. In this year also, Kayser described and figured all 



Kayser, the Graptolite forms hitherto recorded from the Harz 



Mountains from the beds lying at the top of the so-called 

 "Untere Wieder Schiefer," and below the Haupt Quartzite. 

 /.in- geol. Specialkarte These Graptolite-bearing beds he still considered to be of 

 v. Preussen u. d. Lower Devonian age. The forms figured are only frag- 



ThiiringischenStaaten, mentary, but they appear to be correctly identified on the 

 W. 2, heft 4. whole;' they include: (1) M. Nilssuni, (2) M. convolutus, (3) 



.1/. Halli, (4), M. colonus, (5) M. dubius, (('») M. Sagittarius, and (7) M.jaculum? 

 \\r considers that M. dubius is identical with Roomer's species M. Jungsli, M. 

 pulydonta, M. obliquo-truncatus, and M. subdentatus (pars). 



1878-1879 ^ large number of genera and species of the Dendroidea 



Spencer, are described by Spencer, from the Niagara formation. No 



" Graptolites of the figures are given. 

 Niagara formation," '|'| l( , Qew g enera are Calyptograpsus, Rhizograpsus, 



' Canadian Naturalist.' . ,-. mi /* / i 



Acantnograpsus. I he new species are UaLyptograpsus 



cyathiformis, < '. subretiformis, Rhizograpsus bulbosus, Dictyonema tenella, Acan- 



