368 



BRITISH GRAPTOLITBS. 





Figs. 230 a-c.-Monogmptus hohemicm (iJarr.). Affinities. — Moiiog. bokemiciis is a perfectly 



r?^/' ^ distinct and well-marked species wliicli 



should not Ijo confounded with any other 

 Monogrcqyhis. 



Horizon and Locdlities. — Lower Ludlow 

 Shales (zone of M. Nilssoni). Lake Dis- 

 trict : Helm Knot, Dent, etc. Wales: Dee- 

 side Slab Quarries, Moel Ferna. Welsh 

 Borders : Aberedw Hill, Builth ; River Irfon, 

 Builth ; Vicarage Road, Builth, etc. Ludloin 

 District : Elton Lane ; Elton-Evenhay Lane ; 

 Elton-Ludlow Road, etc. 



Associates, etc. — Moiiog. boltemicas is a 

 fairly common fossil in the Lower Ludlow 

 Shales of many localities, but especially in 

 the zone of J/. Nilssoitt. It occurs in this 

 zone associated with Moitorj. Nilssoni, M. 



coloiiits, M. varians, and Gothog. spinosus ; and Avith M. scanicus, M. cJtiinaera, and 



M. tumesceihs at higher horizons. 



Collections. — Sedgwick Museum, Lapworth, and the Authors, etc. 



«. Proximal end, sliowing sicula. Figured 



Quart. Journ. Gool. Soc, vol. Ivi, p. 481, 



fig. 25 h. Elton-Ludlow Road; Lower Ludlow 



Shales. Coll. Wood. 

 h. More distal thecce in relief. Figured Quart. 



Journ. Geol. Soc, vol. Ivi, p. 484, fig. 25(1. 



River Irfon, Builth ; Lower Ludlow Siiales. 



Coll. Wood 

 c. Tliecse of extreme distal portion. Enlarge- 



numt of part of Plate XXXVI, fig. 4 d. 



Monograptus concinnus, Lapworth. Plate XXXVI, figs. 5 a — e. 



1876. Monogra})tus concinnus, Lapwoi-th, Geol. Mag., dec. ii, vol. iii, p. 320, pi. xi, figs. 1 a — e. 



Polypary several cm. in length, with incurved proximal portion and slight 

 ventral curvature distally, gradually widening from a slender proximal 

 end to an average breadth of 1 mm. Theca3 twelve to ten in 10 mm., 

 simple short tubes expanding in the apertural region, overlapping one- 

 third to one-half their length, and with wide, even and everted apertural 

 margins. 

 Description. — The polypary appears to be always more or less curved, but the 

 curvature is perhaps most pronounced proximally ; it widens gradually from a 

 very slender proximal termination, but maintains a uniform breadth for a con- 

 siderable distance in the distal portion. 



The thecae are short, broad tubes, about 1"5 mm. in length in the maturer part 

 of the polypary, and in many respects resemble those of M. nudus, the appearance 

 of an excavation being heightened b^^ the ventral curvature of the polypary. 



Affinities. — Monog. concinnus may always be distinguished by the form of 

 the polypary with its pronounced curvature, which contrasts effectively with 

 the straight and rigid form of M. nudns. Fragments of M. concinnus, however. 



