HISTORY OF RESEARCH. v 



M<mograptns jirioilou (Broiiii). Walcli refers to tliem as a new species of "small 

 denticulated Ortlioceratites," distinct from DciiffiUfn'. (jcnirnhiti. "The nnniLer of 

 chambers appears to be equal in all those of the same leno-th, aiid those hio-her up 

 are narrower than the basal ones;" but the siphon, he wi'ites, has not yet been 

 found. Both forms figured by Walch probably come from the same locality, 

 near Stargard, Mecklenburg, from the grey limestone of the Northern Drift. 

 Walch does not name either of his species. 



,„ , We find no further mention of Graptolites for the next 



Wahlenherq, half-ceutury. But in the year 1821 Wahlenberg recognised 



"Petriticata Telluris the fact that at least one of the forms classed by Linnaeus as 



Succanaj," 'Nova Acta Graptolithus (namely, G. scalaris) was a true fossil. But he 



Reg. Soc. Scieutarum agrees with LinnEeus that none of the other forms (with the 



exception of G. Sagittarius) embraced by him in his group 



Graph tJithus (or bodies which " simulate fossils ") are fossils in the true sense of 



the word. 



Nevertheless, while agreeing with Linnaeus in this general opinion, Wahlenberg 

 boldly employed the term Graptolitlius for the true fossils originally figured by 

 Linnaeus as Graptolithus in the ' Skanska Resa,' and established these as the original 

 types of the palteontological genus Grapiolitlius or Grraptolites in general. In this 

 he has been followed by all subsequent palgeontologists, and the term Graptolites 

 has been consistently used ever since for all those fossils which are presumably 

 identical with or allied to Linngeus' GraptolUlms scalaris. 



Wahlenberg had the same idea of the nature of the Graptolites as Walch had 

 previously held, and believed them to be true Ortlioceratites. He noticed their 

 frequent association with undoubted Ortlioceratites in the up})er shales of Vestro- 

 gothia, and believed that it was possible to trace all the intermediate stages between 

 the large calcareous forms of Orthoceras, and the very small membranous and 

 " apparently translucent varieties " which Linngeus had described as GraptoUtliUS 

 scalaris. He gives a description of what appears to be Linnasus' G. scal((i-is under 

 the name Ortlioceratites tenuis in the following terms: — "It has a maximum 

 breadth of barely a line, a length of one inch, and a linear shape. Its joints 

 here and there have been separated from each other alternately, and have been 

 turned over so that they have imprinted in the shale circles smaller than 

 mustard seed. Longitudinal types, instead of a siphon, show a definite medullary 

 nerve (thread), to the sides of which dissepiments are attached, often opposite each 

 other, as in their natural position, but sometimes alternating. This (alternation), 

 however, might have been brought about by disturbance or by obliquity." These 

 small fossils (the Graptolites), he writes, occur frequently alone, only rarely mixed 

 with the larger forms (of Orthoceratites) . He concludes from this that they " li^•ed 

 on as such through the period of the upper shales, after the extinction of all the 

 large Orthoceratites." 



