138 Dr. H. A. Nicholson on some Fossils 



Clonograpsus, Hall. 



In tlie course of last winter, when preparing the first part of 

 my 'Monograph of the British Graptolitidte,' I wrote to Prof. 

 Hall asking him to propose a generic name for forms like his 

 Graptolithus Jiexilis and G. rigidus, which are clearly entitled 

 to be placed in a separate genus. Prof. Hall's reply unfortu- 

 nately reached me too late to be available in the above men- 

 tioned publication, and I therefore left these forms temporarily 

 in the genus DicJiograpsus. I take the present opportunity, 

 however, of defining the species in question under the generic 

 name of Clonograpsus {kXodVj a twig) proposed for them by 

 Prof. Hall. 



The characters of the genus are as follows: — Frond composed 

 of numerous (more than eight) stipes proceeding from a common 

 funicle, on the two sides of which they are symmetrically 

 arranged ; the frond dividing dichotomously and the pro- 

 cess of division going on after the cellules are developed, 

 till ultimately there may be produced from sixty-four to one 

 hundred and forty-four simple celluliferous stipes. No central 

 disk. 



The genus Dichograjjsus, Salter, will now contain only those 

 GraptoHtes in which the frond consists of eight simple stipes 

 proceeding from a funicle, the divisions of which are some- 

 times enveloped in a corneous disk. The celluliferous stipes 

 in this genus do not subdivide or branch. 



The genus Loganograpsus^ Hall, again, will embrace those 

 compound Graptolites in which the frond consists of from eight 

 to twenty -five simple stipes which do not subdivide, and which 

 are sometimes united at their bases by a corneous disk. 



From both of these genera Clonograpsxis is distinguished by 

 the great number of stipes composing the frond (sixty-four to 

 one hundi'ed and forty-four in the typical forms, but fewer in 

 others), by the fact that the celluliferous stipes themselves sub- 

 divide, and by the apparently uniform absence of a corneous 

 disk. 



The only undoubted species of Clonograpsiis from the Quebec 

 group are C. flexilis, Hall, and C. rigidus^ Hall, both of which 

 occm* in great plenty in the shales of Point Levis. It is also 

 probable that the Graptolithus Richardsoni and G. ramulus of 

 the same author, from the same formation, likewise belong to 

 this genus. Of the Graptolites of the Skiddaw series of the 

 north of England, the Dichograpsus midtiplex, Nich., un- 

 doubtedly belongs to Clonogrcqjsus, and DicJiograpsus reticu- 

 latus, Nich., may likewise, in all probability, be placed in this 

 genus. 



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