MONOaRAPTUS. 379 



approaches M. tumPHcens and M. coIomt>^, l)ut from both these species it may 

 be readily separated by the characters of the proximal end ; from M. fttinesceits 

 it differs also in the entire absence of curvature, and from M. colon us not only in 

 this particular but also in the simple character of the early thecse. 



Horizon and Localities. — Wenlock-Ludlow (zones of Gijrkxj. Lnnihjrent and 

 M. vulgar is). 



N. Wales : Road to Deeside Slab Quarries near Tyn-Craig, Moel Ferna. 

 Welsk Borderland : Trefnant — Middletown Jirook, Long Mountain, etc.; River 

 Irfon near Mill, Builth, etc. 



Associates, etc. — Manor/, vulgaris is an abundant fossil in some localities at the 

 very base of the Lower Ludlow Shales, where it occurs either to the exclusion 

 of all other well-known forms or associated with M. duhius and (Joihog. nassa. It 

 is also found occasionally in the highest Wenlock Shales associated with Cyrtog. 

 Lundgreni and Monog. Flemingii var. Up to the present time it has only been 

 recorded from N. Wales and the Welsh Borderland. 



Collection-^. — The Authors. 



Var. curtus, nom. nov. Plate XXXVII, fig. 11. 



1900. M. vuhjaris, var. ft, Wood, Quart. Jouru. Geol. Soc, vol. Ivi, p. 457, pi. xxv, fig. 4. 



In addition to Monog. vulgaris itself there is found a well-marked variety, but 

 at a slightly higher horizon than the typical form ; this is shorter and narrower, 

 and has a distinct tendency to ventral curvature of the proximal portion. 



The mature thecie are shorter (2 mm.) and narrower, and are only about three 

 times as long as wide. 



Horizon and Localities. — Ludlow (zone of M. Nilssoni). 



Long Mountain : Lane Farm. Ludlow District : Elton Lane ? 



Associates, etc. — Var. curtus occurs rarely in the Ludlow Shales associated with 

 Monog. holcemicus. 



Collections. — The Authors. 



Monograptus tumescens, Wood. Plate XXXVII, figs. 12 a — d. 



1868. GrajjtoUtes colonus, Nicholson, Quart. Jouru. Geol. Soc, vol. xxiv, p. 540, pi. xx, figs. 9 — 11. 

 1889. Pristiograptus frequens ?, Jaekel, Zeits. d. d. geol. Gesellsch., vol. xli, p. 669, pi. xxviii, figs. 1, 2. 

 1900. llonograptus tumescens. Wood, Quart. Jouru. Greol. Soc, vol. Ivi, p. 458, fig. 11, pi. xxv, 

 figs. 5 A, B. 



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

 curvature in the proximal portion, widening rapidly to an average 



