398 



BRITISH GRAPTOLITES. 



Figs. 2()5 a and h. — Monoiiraphis 

 Rocmeri (IJarrande). 





The thecal arc also markedly cliaracteristic of the species, only two show traces 

 of ogee curvature and retroversion of the apertural extremity, in neither case 



very pronounced. The great length of the thecte in 

 proportion to their breadth in the mature portion 

 of the polypary is most noticeable, as is also their 

 high angle of inclination and amount of overlap. 

 There is occasionally a tendency to diminish in 

 breadth in the distal portion of the polypary, l)ut 

 this may only signify immature development of the 

 tliecEe. 



Affiiiitics. — Monog.Iioemcri is undoubtedly closely 

 related to M. coloims, but it can be easily separated 

 from that species by the greater length of the 

 mature thecEe. 



Horizon and Localities. — Lower Ludlow >Shales 

 (zones of M. Nilssoiil and 71/. scan teas) and their 

 equivalents. 



Ludlow District: Elton Lane; Elton-Ludlow 

 Road. Ljonrj Mountain District: Ti-efnant-Middle- 

 town Brook. Tjal-e District : Helm Knot, Dent. 

 Staffs. : Dudley, Walsall. Welsli Borders : Aberedw 

 Hill, Builth. 



Associates, etc. — Monog. lloemcri is not a common 

 fossil in British rocks ; it occurs, however, in the zone of M. Nilssoni associated 

 with the zone fossil and M. colonus, and at a higher horizon with M. scanicus and 

 M. chimsera. 



Collections. — Sedgwick Mnsenm, Univ. of Birmingham, Lapworth, and Wood. 







a. Proximal end, showing sieula. En- 



laigpiiient of reverse side of part of 



PI. XXXIX, fig. 2 a. 

 h. Distal tliecaj in relief. Helm Knot, 



Dent ; Coniston Grits. Sedgwick 



Museum. 



Monograptus chimsera (liarrande). Plate XXXIX, figs, o a — (/. 



1850. Gra^itolithiis cJiiiiavra, BarrauJo, Giapfolites de BoLeuic, p. 52, pi. iv, figs. 34, 35. 

 1889. Pristiufjraptus colonus, Jackel (?), Zeitschr. tl. dculscli. geol. Gcsellseb., vol. xli, p. 674, pi. 

 xxviii, fig. 8. 



1899. Mvnograj'tns chit)i;vru, Pcrucr, Etudes sur les Graptulitos dc Bolieiiie, pt. iii, sect, b, p. 14, 

 pi. xvii, figs. 15 a, h. 



1900. Mo)iO(jrajifus clilmivra, Wood, Quart. Journ. Gcol. Soc, vol. Ivi, p. 471, pi. xxv, figs. 18 a — d. 



Polypary 2 — 4 cm. in length, straight distally, but with slight ventral curvature 

 in the proximal portion, increasing rapidly in Avidtli at first and then more 

 gradually till the maximum breadth of 2 mm. is attained. Theca3 thirteen 

 to eleven in 10 mm., ajjpearing as sonicAvhat hexagonal prisms with spined 



