HISTORY OF RESEARCH. lvii 



(11) D. folium; (12) Climacog. scalaris ; (13) Eetiolites Geinitzianus; (1 I) Dulymog. 

 Murchisoni, (lb)D.crucialis; (16) Biclwg.aranea; (17) Phyllog.ilicifolius; (18) Cladog. 

 linearis; and three new forms, viz. : (19) Gr. Hisingeri (a name which he suggests 

 for Hisinger's Prionotus Sagittarius to "prevent further confusion"), (20) 

 Gr. Cling ani, and (21) Didymog.,(I)icellog.) elegans. These, however, are not 

 described. 



In the diagnoses of the various forms of Graptolites, Carruthers employs for 

 the first time in scientific literature the same nomenclature as that already pro- 

 posed by Huxley and Allman for the Hydrozoa in general, using such tonus as 

 " polypary," " ccenosarc," " hydrotheca," etc., in his descriptions. This plan has 

 since been followed by the majority of palaeontologists. 



He agrees generally with Barrande's account of the structure of a typical 

 Graptolite, such as Monog. Boemeri and .1/. priodon, but he notices " what seems to 

 be a septum at the base of each hydrotheca," in Gr. Sagittarius and Gr. latus. He 

 calls attention to certain specimens of Viplog.pristis which he found on one slab, in 

 which the "naked axes met." This circumstance suggested to him the "possibility 

 of the supposed perfect specimens of Diplograpsus being only fragments of more 

 complex forms" (as in Retiograptus) . He thus, like Emmons (p. xxxviii), 

 anticipated in theory Kuedemann's subsequent discoveries. Carruthers, however, 

 finally rejects this idea as being "anomalous and improbable." 



He also discusses what is known or surmised about the development of the 

 Graptolites, and figures certain young forms with their "radicle," and also a 

 specimen of a form closely resembling those examples of Diplograpsus bearing 

 "reproductive sacs" figured by Hall, but in this case only the interlacing fibres 

 are seen, not the sacs themselves. 



As regards the affinities of the Graptolites, he considers that they are more 

 closely allied to the Hydrozoa than to the Polyzoa or any other group of animals, 

 the polyps rising directly from the cuenosarc. 



18( » 7 In an appendix- to the fourth edition of Murchison's 



Carruthers, ' Siluria,' which is dated 1867, Carruthers gave a second and 



Murchison's ' Sihiria,' briefer account of the Graptolites in general, and also a 

 4th edit. classification. This classification is essentially the same as 



that given by him in his paper in the 'Intellectual Observer ' already cited ; the 

 only difference is that he subdivides his Section I into those with their — (a) 

 polyparies simple and (/>) polyparies compound ; his Section II into those — (a) with 

 a slender solid axis and (/>) without an axis (Retiolites). 



He figures (1) Retiolites Geinitzianus, (2) Dichog. Scdgivickii, (3) Dicranog. 

 ramosus, (4) Phyllog. angustifolius, ("■•>) Cladog. linearis', and also three new 

 species — (6) Cyrtog. Murchisoni, (7) Ra strites maximus, (8) Dendrog. lentus. (The 

 last form in reality belongs to the genus Clonograptus.) lie again in this article 

 argues in support of the Hydrozoal affinities of the Graptolites. 



