HISTORY OF RESEARCH. xxiii 



Immediately after the api)earaiice of Barraiide's memoir 



g^^^.gg on tlie Bohemian Graptohtes, Sness ])ublis]ied tlie rcsnlts of 



" Ucber BohiuisclKj ^li''^ own researches on this subject. His lahours covered 



Graptolithen," nnich tiie same ground as tliose of Barranck' ; Ijut liis 



' Naturwisseusc'li. Ab- paper, though long and detailed, did not materially advance 



haudl. von HaidiugcT,' ^|^^ gubiect beyond the point to which Barrande's researches 



and conclusions had already brou.ght it, and the figures upon 



the })lates wliich illustrate his paper are indifferent. We may here notice those 



points respecting which Suess added to or differed from the results already arrived 



at by Barrande. 



Mode of Existence. — In dealing with the character of the rock in wdiicli tJie 

 Graptolites occur, Suess points out that the shales are often very carbonaceous, and 

 frequently contain balls of anthraconite, and he suggests that these balls may have 

 been formed l)y the I'olling in the mud of the remains of marine plants. This is 

 interesting in the light of later opinion concerning the mode of life of Graptolites, 

 and the recent view that they were attached to seaweeds. 



Chissijirafinii. — As regards the classification of the Graptolites, that of Suess 

 differs consideraljly from that proposed by Barrande. He suggests that there are 

 only three genera, viz. — 



1. lletiolites (in Barrande's sense) ; 



2. PetaloIWius (including the sub-genus Dijn-ion of Barrande and the sub-genus 

 Dijilograpsis of M'Coy) ; 



3. Graptolitlms (embracing forms having only one row of cells). This genus is 

 subdivided into three sub-groups, namely, those having — 



{(t) a strong axis bent into a fixed curve in one plane, and their cells always in 

 contact ((tt. holieniicns) ; 



(h) an axis at the older end bent into a definite conical screw line ; at the 

 younger end thread-like ; cells in contact when fully developed, not in young stage 

 {Gr. profi'us) ; 



(c) an axis thread-like and curved; cells not in contact (Ba.^f riles). 



He agrees with Barrande (and is even more consistent in this respect) in con- 

 sidering the narrowest end of the polypary as the younger, and therefore always 

 figures it Avith that end uppermost. 



Structure. — Suess described the genus lletiolites and its species It. Gciuitziaims 

 in nmcli detail, but his explanation of its structure is markedly different from that 

 of Barrande. According to Suess, the axis, which is " sometimes disthict, sometimes 

 almost invisible, not rigid, but flexible," gives rise to alternating secondary branches 

 at regular intervals. As the polypary increases in size, interspaces appear between 

 the secondary branches, and these are formed by the splitting of the branches into 

 two parts from the centre towards the outside. These interspaces arc then 

 divided l)y five or six strong transverse walls at right angles to the secondary 



