394 BRITISH GRAPTOLITES. 



Horizon and Localities. — Lower Ludlow Shales (zone of M. Nihsoni). 



LtiiJIoir JJisfrict : Eltoii-Eveiiliay Lane; Elton Lane; Stormer Hall. 



Associates, etc. — Var. compactus has up to the present time only been recorded 

 with certainty from the Ludlow District; it may also, however, occur in the 

 Abberley Hills, but this is uncertain. It was found in the zone of M. Nilssoni 

 associated with the zone fossil, M. cliinixra var. Salioeyi, and M. varians var. immilus. 



CoUeclions. — Sedgwick Museum, Wood. 



Var. ludensis (Murchison). Plate XXXVIII, figs. a—c. 



1839. Gra2)toIitJius liiderisis, Murcliisou, The Silurian System, pi. xxvi, fig. 2. 



1879. ? Graptolithus ludensis, Quenstedt, Petrefactenlcuiide DeutseliL, vol. vi, pp. 192 — 193, pi. cl, 



fig. 29. 

 1900. Moiiograpfus colonvs, var. ludensis, WooJ, Quart. Jouru. Geol. Soc, vol. Ivi, p. 465, pi. xxv, 



fig. 11. 



As has ah'eady been made clear l)y Wood (loc. cit. supra) there has been 

 considerable misapprehension concerning this form ; the type specimen, now in the 

 collection of the Geological Society of London, is badly preserved, and our 



personal collection and examination of material from 



Fig. 202. — Monograptus colonus,yn.v. it i p ^ ■ ^ -\t -\ ■ 



ludensis (Mnrcinson). the Same locality as that irom which Murchison 



r'^3 procured his original specimens have unfortunately 



I^y^v- not completely solved the problem. The specimens 



4./^. are all preserved in a hard calcareous sandstone 



? /A which w^eathers deeply, and it is only on the 



\\^/ weathered surface that the Graptolites can be seen. 



lyT As yet it has been impossible to determine with 

 accuracy whether the proximal thecas really re- 



Proximal end, showing sicnla. Enlarge- ./ x ./ 



ment of part of PI. xxxviii, scmblc tliose of Monoo. coloiius ; one at any rate 



fig. 9 a. ' 



appears to show ogee curvature and retroverted 

 apertural extremity, but wdiether or not there are more thecae of this type is 

 uncertain. The mature thecse appear to be somewhat larger than those of M. 

 colonus itself, being apparently quite six times as long as wide. For the present 

 it seems best to retain Murchison's name for the specimens from Llanfair, and to 

 regard them as constituting a variety of M. coloiius. It might, perhaps, be urged 

 that if M. ludensis and M. colonus probal)ly belong to the same species, the older 

 name — M. ludensis — should be applied to both. But Barrande's name — M. colonus 

 — has been classic in paljEontological literature for the last half century and more, 

 and has obtained such acceptance among Graptolithologists in general that the 

 change w^ould be pedantic. 



■Horizon- and. Locality. — Lower Ludlow (?). 



