HISTORY OF RESEARCH. cxxv 



" which radiate from an axial club-shaped protuberance within the vesicle, to which 

 they are joined by the filiform prolongation of their pointed ends." Ruedemann 

 compares these vesicles with the gonangia of recent Hydrozoa. 



(4) Overlapping the gonangia and even the proximal ends of the stipes, there 

 is an organ which he compares with the air-bladder or pneumatocyst of the 

 Discoideas and which he regards as having acted as a float. 



(5) The siculae " at the time of developing the first two hydrothecae, possess a 

 quadrangular plate, joined by a small node in the centre to the end of the filiform 

 proximal process"; while at a slightly later stage of development four oval 

 impressions can be seen around the central node. This quadrangular plate (or 

 probably vesicle) develops into the pneumatocyst, the central node into the funicle 

 and central disc, and the small oval impressions probably indicate the gonangia. 



(6) From the position of the siculse at the remote end of the stipes the " so- 

 called proximal sicula-bearing end of the single stipes appears in the compound 

 colonial stock as the distal one." " The stipe grows backward towards the centre 

 and the sicula is carried to the distal end." 



(7) With regard to the affinities of the -Graptolites, Ruedemann points out that 

 by the " possession of a pneumatocyst and the arrangement of the reproductive 

 organs at the bases of the stipes, the colonial stocks of Diplograptus had a general 

 similarity to those of certain Siphonophora, while the chitinous structure of the 

 hydrothecse and gonangia can be only referred to the Sertularians." 



1895. Matthew described in 1895 some new species of Cloiw- 



Matthew, O. F., graptus, Bryograptus, etc., from the lower part of Division 3 



" Two new Cambnau of the St. John Group. Clonograptus proximatus, sp. nov., 



Graptolites with Notes resembles Qlonog. tenellus in many respects ; unlike the latter 

 on other Species of . . .. 



G • t l't'l f th t ^ occurs m association with Dictyonema fiabeUiforme and not 



Ace," 'New York Acad, above it. Matthew distinguishes Clonograptus from Bryo- 

 Sci. Trans.,' August graptus by its being " devoid of the sicula, or with the sicula 

 29tn - obscure, absorbed, or merged in the funicle." Four species of 



Bryograptus are described and figured : Bryog. patens, B. spinosus, B. lentus, B. 

 retroflexus? A fragment of Callograptus is figured and two specimens of 

 Dictyonema fiabeUiforme, showing "short rootlets developed from the proximal end 

 of the sicula." As regards the occurrence of the last-named form in America, 

 Matthew states that the species was not a " solitary Graptolite," as in some parts 

 of Europe, but was associated sparingly with Bryograptus and Clonograptus. 



As to the phylogenetic relationships of the Graptolites he writes, "the succes- 

 sion of the Dichograptidas in the Cambrian and Lower Ordovician is a good 

 exemplification of increased condensation of structure due to selection ; for the 

 many-branched forms of the former are gradually replaced by the Tetragrapti and 

 these by the Didymograpti of the Upper Arenig." He repeats his former view 

 that the Bryograpti were the ancestors of Dictyonema. 



