lxxii BRITISH GRAPTOLITES. 



edges." These fibres, he suggests, may have been slender tubes. One specimen 

 appears to indicate that the capsule may have been composed of two " membranes 

 joined together at their edges through which the fibre has run." 



He also figures two young forms of Diplograpsus, apparently lying within one 

 of the capsules, but points out that they are large enough to have " entered on an 

 independent existence." 



He remarks on the agreement of this specimen with the capsules figured by 



Hall, but not with those figured by Nicholson, of the existence of which he seems 



to doubt. Their possible bearing on the affinities of the Graptolites is discussed, 



and Hopkinson considers that they confirm the near alliance of the Graptolites 



to the Sertularina, " though all the characters of their reproductive organs are 



not found in any one genus of the Hydroida." 



1871. To the Meeting of the British Association of 1871 



Lajjworth, Lapworth communicated a list of the characteristic Gala 



" On the Graptolites of Graptolites of South Scotland, and described but did not 



,, . L 10Up ' figure two new species : (1) Betiolites obesus and (2) Grapto- 



' Brit. Ass. Report.' ° l x / , , '. 



lithus socialis (afterwards identified with M. exiguus, Nich.). 



1871 In 1871 W. H. Baily contributed some palasontological 



Baity, W. H., notes on the Silurian rocks of the country round Downpatrick 



' Memoir of the and the shores of Dundrum Bay and Strangford Lough. In 



Geological Survey of dark -grey slates near Downpatrick and Portaferry he 



recognises three Graptolite species, one Gr. priodoii and two 



new forms which he named (1) Or. plumosus and (2) Gr. gradatus. Gr. plumosus 



is certainly the M. exiguus of Nicholson, while Gr. gradatus is allied to M.communis 



(LapAv.). Both species are described and figured. 



!g71 In the same year Richter published a paper giving the 



Bidder, results he had arrived at in the continuation of his work on 



" Aus dem Thiiring- the Thiiringian Graptolites. He gives a general revision of 



schen Schiefergebirge," hig viewg on their strn cture, development, affinities, etc., and 



" ' , "... the new points brought out by him may here be briefly 



Heft j summarised. 



He founds a new genus which he names Triplograptus, 

 with a single species (1) T. Nereitarum. (This, however, is now known not to be 

 a Graptolite and need not, therefore, be discussed.) He also describes and figures 

 Thi'iringian examples of older species, viz. (1) Diplog. pristis, (2) D. teretiusculus, 

 (3) Monog. cf. Sagittarius, (4) M. priodon, (5) M. gemmatus, (6) M. peregrinus, 

 (7) PhyUogvaptns, and in addition three new forms : (8) Diplog. pennatulus, 

 (9) Monog. crenatus, and (10) M. chorda. Most of the species are readily recog- 

 nisable from his illustrations. 



The greater part of Richter' s paper deals with the structure of the Graptolites. 

 He states for the first time in the history of graptolitic research, that the skeleton, 



