cxliv BRITTRH GRAPTOLITES. 



clears up 1 1 1 o previous confusion as to the exact identity of this species, showing 

 that Barrande had originally included three different species under this name. 



The group Prosopodes includes Monog. Boemeri, M. dubius, M. colon us, M. 

 chimf&ra, M. testis, M. bohemicus, and the following new species : M. Kayseri, M. 

 hercynius, M. gotlandicus, M. subcolonus, M. largus, M. transgrediens, M. 

 vicinus, M. ultimus, M. clavulus, M. Fritschi, M. bohemicus var. rarus. 



The group Helicopodes includes only Monog. spiralis var. subconicus. 



The group Orthopodes contains M. crenulatus and M. vomerinus. 



The genus Gyrtograptus is represented by Gyrtog. flaccidus, G. Lundgreni, 

 G. Marchisoni, G. Garruthersi, and the new species G. tubuliferus. 



Under the genus Uetiolites Perner describes Retiolites Geinitzianus, R. (Gotiio- 

 graptus) nassa, and Stomatograptus grandis. 



189g . A memoir of very great importance as regards its bearing 



Peach and Home, ori the range and zonal value of the Graptolites was published 



" The Silurian Eocks of in 1899. This was H. M. Geological Survey Memoir on the 



Britain," vol. i, « Silurian Rocks of Scotland." The officers of the Survey 



confirm Lap worth's conclusions respecting the zonal distri- 

 bution of Graptolites in the rocks of the Southern Uplands, and employing these 

 fossils as zone indices, they work out and illustrate in detail the geology of the 

 districts in which they occur in the course of their description of the entire Upland 

 Sequence. 



1899. 



Tbmquist, j n lg99 Tornquist published the second part of his 



. ,, „ .%,.'.. Monograph on the " Graptolites of the Scanian Rastrites 

 of the Seaman Jtiastrites . 



Beds" 'Acta Univ. Beds." This is devoted to the study of the Monograptidas. 



Lund.,' vol. xxxv. 

 Tornquist employs throughout the terminology adopted by him in the first 

 part of this work. 



The following synopsis is given of the species of Monograptidas described, 

 the grouping being based mainly on the form of the polypary and the character of 

 the sicula and thecae. 



a. All the thecas of the same type ; each wholly adnate to the proximal wall of 

 the theca next succeeding. 



(a) Sicula attaining a length of more than 4 mm ; rhabdosome curved. 



M. gregarius and M. acinaces. 

 (/>) Sicula not exceeding 2 mm. in length ; rhabdosome stout, straight. 

 M. leptotheca, M. jaculum, M. nudus, M. regularis, n. s. 



(c) Sicula not exceeding 2 mm. in length ; rhabdosome stout, proximally 



incurved. M. inopinus, n. s. 



(d) Sicula not exceeding 2 mm. in length ; rhabdosome arcuate, gradually 



widening from the proximal extremity. M. tenuis. 



