HISTORY OF RESEARCH. xv 



(the single-sided forms), and he proposes the now name Diplograpsis for those 

 GraptoUtes which have denticles on both sides. This suggested nomenclature Avas 

 soon generally adopted, bnt there has been considerable discussion among subse- 

 quent writers as to whether the original Graptolite described by Linngeus as 

 G. scalaris was not in reality a l^iserial form, and that consequently the generic 

 name GraptoUtes ought rather to be used for biserial than for uniserial forms. 



M'Coy gives figures of three new species of Graptolites, namely, Gr. lobiferus, 

 Or. millepeda, and Diplogra2ms rectangularis. He does not, however, give any 

 description of these forms. 



Nicol, in a paper which is mainly stratigraphical, de- 



j^l^^j scribed and figured a ncAV species of Monograptus, GrajitoUtcs 



" Observation on the griestonensis. Descriptions are also given of Grai)tolites 



Silurian Strata of the convolutns (which he Considers to be identical with Gr. sjuralis 



S.E. of Scotland," j^j-^j]^ Q^^ ludensis), and a " foliaceous species " which, " if a true 



guar . ^ ouin. eo . Graptolite, seems undoubtedly a new species." To this he 



gives the name Gr. laxus. He points out " that it so closely 



resembles some plants of the moss tribe (Hypnum) as to render its real character 



doubtful." 



Nicol gives a brief review of the opinions previously held by palseontologists as 

 to the true character of Graptolites, and asserts that while the general opinion is in 

 favour of their being Polyparia, he finds that some are carbonaceous, some 

 horny ; and he throws out the suggestion that these remains may have belonged to 

 animals of more than one class, and that " some of them may have been internal 

 organs, rather than the external axis of a variety of polypifer." 



In 1850 Naumann gave four woodcuts of Graptolites, and 



also figured seven species in an illustrative lithographic plate. 



'T 1 -1 -h 1 -'r ^^^ these, however, are bad copies of figures taken either from 



o-nosie ' vol. i. Murchison's ' Silurian System ' (Gr. ludensis, Gr. MurcJiisoiii) 



or from Geinitz's illustrations in the ' Neues Jahrbuch ' for 



1842 {(Jr. foliam, Gr. convolutus, Gr. Sagittarius, Gr. priodon, and Gr. scalaris), and 



they give no new information. 



Richter's first contribution to the study of the Graptolites 



jll^j^f^^. was published in 1850, and dealt mainly with ({uestions of 



" Aus cTer Thiirin- classification and structure. His classification is very similai- 



gischen Grauwacke," to that suggested by Geinitz in ] 846. He divides Graptolites 



' Zeitsch. d. Deut. geol. -j^^-q ^^^q groups: (I) curved (or single-toothed), and (II) 



^^^ ■' ■ "■ straight (or double-toothed) ; and suggests a possible third 



class, or " closed." Under the first group (curved forms) he includes two species : 



(1) GraptoHilms Sagittarius, of which he gives seven figures; and (2) Graptolithus, 



species unnamed. Three of his figures of Gr. Sagittarius are probably drawings 



of examples of Monograptus ci/plius, while three others are clearly of forms 



