652 J. HOPKINSON AND C. LAP WORTH on the graptolites of 



near their extremities, their maximum width being one six- 

 teenth of an inch; hydrothecae about 12 to the inch, three 

 times as long as wide, their outer margins concave, free for the 

 greater part of their length, and inclined to the axis of the 

 branches at an angle of about 30° ; apertural angle 60° to 90°. 

 In its slender recurved branches and acutely pointed hydrothecce 

 this species is widely separated from all the others of its genus 

 except T. fruticosus, Hall, from which it differs in its more slender 

 and often widely divergent branches, in its minute sicula, and in its 

 more pointed and more distant hydro thecse. 



It occurs in profusion, though usually very badly preserved, and 

 most frequently in separated branches, a few feet lower than the other 

 species of the genus here described. It was discovered by Mr. Hicks, 

 who was the first to recognize its distinctness from T. fruticosus, 

 and after whom we have therefore much pleasure in naming it. 

 Loc. Middle Arenig, Whitesand Bay. 



Genus Clematograptus, Hopkinson, gen. nov. 

 (Derivation : KXijfia, a branch ; ypa^w, I write.) 



Polypary compound, bilaterally subsymmetrical, consisting of nume- 

 rous (never less than than thirty -two') normally simple closely 

 approximating branches, radially disposed, arising singly or in 

 groups from both margins of an irregularly and repeatedly 

 branching funicle ; hydrothecce of the type of those o/Dichograptus. 



This genus is nearly related to Loganograptus and Clonograptus. 

 From the former it differs in the much greater number and inequality 

 of the primary divisions of the funicle, and from the latter in the 

 manner in which the division and subdivision of the funicle is carried 

 out and the branches ultimately given off. In Clonograptus the 

 compound funicle invariably branches and rebranches in a regularly 

 dichotomous manner, each new division being attained by exact and 

 equal bifurcation, the consecutive bifurcations at the same time being 

 separated by comparatively wide and regular intervals. In Clema- 

 tograptus, on the contrary, the subdivision of the funicle is carried 

 out in a very irregular manner, the branches being finally given off 

 at inconstant but pretty close intervals, either along one or both sides 

 of the branching funicle, or even in dense groups. The rigid spread- 

 ing polypary in Clonograptus is thus remarkable for the symmetrical 

 arrangement of its parts, while in this respect the closely set but 

 lax Clematograptus is correspondingly unique in its irregularity. 



The only undoubted species of Clematograptus known at present are 

 the C. implicatus of this memoir, and the C. (GraptolitJius) multi- 

 fasciatus of Prof. Hall. 



Clematograptus implicates, Hopk., sp. nov. PI. XXXIY. fig. 1. 

 Loganograpsus (?) implicatus, Hopk. Brit. Assoc. Beport, 1872. 

 Branches very numerous, slender, flexuous, arising from a very ir- 

 regularly repeatedly branching funicle, the divisions of which 

 are as flexuous and irregularly disposed as the branches. 



