lxvi BRITISH GRAPTOLITES. 



generic character, but points out that unfortunately there are no materials in 

 Britain to enable one to determine this. 



Many species of the genus Didymograpstis as thus enlarged are referred to, viz. 

 D. hirundo, D. Murchisoni, I), v-fractus, D. sextans, D. Forchammeri, (8) D. elegcms-, 

 D. moffatensis, I). caduceus, D. bryonoides, IK quadribrachiatus. 



The forms of Dichogmpsus noticed by him are : J), octobrachiatus and 

 D. Sedgwickii. 



He reinstates the genus Cladograpsus for his own G. linearis, refusing to 

 accept Nicholson's generic name of Pleurograpsus, and includes in the genus 

 G. linearis, (9) C. capillaris, and 0. gracilis. 



The forms of Diplograpsus noted and figured are : (10) I). pvixtix ( = 

 D. vesiculosus and IK pJiysopltora), (11) D. minimus, D. anguxtif alius, (12) 

 I). W/iitjirhli (including D. quadrimucronatus, Nich.), (13) D. tricomis, (14) 

 I), cometa (including I), tnbulariformis, Nich.). This last named form he thinks 

 "should perhaps be made the type of a new genus." As regards (15) 

 D. mucronatus, Carruthers suggests that those forms with " several branching and 

 apparently anastomosing processes from the cell mouth," which Hall considered to 

 be the marginal fibres of the reproductive sacs, may really prove to be a distinct 

 species, for which he proposes the name J). Bailyi. Diplog. persculptus is referred 

 to, but not described or figured. 



Two forms of Dendrograptus are noticed : D. furcatidus and (10) D. lent us, Carr. 



Under Climacogr aphis Carruthers gives figures of (17) 0. scalaris and a new 

 species (18) 0. minutus. 



Under the genus Dicranograptus he includes I), ramosus and a new species 

 (19) T>. Clingani, thus for the first time restricting this genus to those forms with 

 a biserial proximal portion and uniserial distal stipes. 



The genus Retiolites, according to Carruthers, possesses no axis or septum. 

 The forms recognised are : Ii. ( '-id nitzia nns and 7k venosus. 



Only one form of Phyllograptus is noticed from Britain, viz. the P. angustifolius 

 of Hall. 



Carruthers' paper is prefaced by a general description of the structure of a 

 typical Graptolite, but this contains nothing new. He, however (as in his paper 

 in the ' Intellectual Observer '), strongly recommends the adoption of the 

 nomenclature already in use for the Hydrozoa, and he consistently employs 

 it throughout this memoir. 



The affinities of the Graptolites are discussed by Carruthers at great length. 

 He considers that the general form of the polypary, its free or attached nature, 

 its chitinous character, are of no systematic value, whereas the presence or 

 absence of a common canal is of very great importance. The affinities of the 

 Graptolites to the Polyzoa are fully considered, but the absence of a common 

 canal in the Cheilostomata, and the fact that the cells are in communication only 



