666 J. HOPKINSOKT AND C. LAPWORTH ON THE GRAPTOLITES OF 



their proximal end into a very short and very wide main stem, 

 from which they originate in a dense mass ; parallel with each 

 other thronghont their length, the radiating almost circular 

 appearance of the polypary being due to their frequent bifur- 

 cation ; sometimes anastomosing frequently, sometimes pro- 

 ceeding for a considerable distance without being conjoined in 

 any way; more than equal in width to the space between 

 them near their origin, but not quite equal to it near their 

 extremities ; hydrothecaB 25 to 30 to the inch, slightly pro- 

 jecting and giving the branches a sub articulated appearance 

 when compressed laterally, and presenting their apertures as 

 minute depressions when the ventral side is uppermost. 



The specific name given to this species suffices to distinguish it 

 from every other species of its genus already known, Callogrwptus 

 radicans (which is not nearly so radiating in appearance) being its 

 nearest ally. In one of the specimens figured (fig. 8 a) the branches 

 form more than half a complete circle. 



Loc. Lower Arenig, "Whitesand Bay, and Road Uchaf, Ramsey 

 Island. 



Callograptus radicals, Hopk. 



1872. Cattograptus radicans, Hopk., Ann. & Mag. Nat. Hist. 

 series 4, vol. x. p. 233, pi. x. 



Diffusely flabelliform, attaining a length of fully six inches, and an 

 extreme width of about the same; branches springing from 

 an elongated, erect, and robust main stem which terminates 

 proximally in a spreading fibrous hydrorhiza ; bifurcating 

 frequently and continuously throughout their length, at first 

 diverging only slightly, but afterwards at wider angles ; ana- 

 stomosing frequently but at very irregular intervals ; hydro- 

 thecse about 20 to the inch, showing only their apertures, 

 which appear as minute oval impressions, the longer diameter 

 of which is parallel with the margins of the branches. 



As this species has been so recently described in the ' Annals of 

 Natural History,' we will here only draw attention to its value as 

 showing that the dendroid Graptolites may be inferred to have been 

 similar in their fixed mode of growth to the recent Hydroids of the 

 suborder Thecaphora, its hydrorhiza being an almost exact counter- 

 part of those of many recent sertularian zoophytes. 



The plate in the 'Annals' being a reproduction by photolitho- 

 graphy of the most perfect specimen of C. radicans we have 

 obtained, may be here referred to as showing the condition with 

 regard to preservation, and the general aspect of nearly all the 

 Graptolites of the Lower Arenig rocks of St. David's. 



Loc. Lower Arenig, Road Uchaf, Ramsey Island. 



Callograptus elegans, Hall. PL XXX YI. fig. 9. 



1865. Callograptus elegans, Hall, Grapt. Quebec Group, p. 134, 

 pi. xix. figs. 1-4 (pi. xviii., fig. 4 ?). 



