MONOGRAPTUS. 



429 



Figs. 291 a and b. — Mono g rapt us un- 

 einatus var. micropoma (Jaekel). 



more distant thecae (ten to nine in 10 mm.) ; the 

 beak of the apertural region is also less conspicuous. 



Horizon and Localities. — Lower Ludlow Shales 

 (zone of M. Nilssoni and zone of J\l. scanicus). 



Shropshire: Elton Lane, Ludlow; Stormer Hall, 

 Leintwardine ; Lower Wilmington, Long Mountain ; 

 Garbett's Hall, Long Mountain. 



Associates, etc. — Var. micropoma occurs chief! y 

 in the zone of M. Nilssoni associated with M. holie- 

 micns, M. Nilssoni, M. varians, var. pumilus, M. 

 dubius and M. chimsera var Salweyi. It also occurs 

 in the zone of M. scanicus. 



Collection . — Wood. 



a. Proximal end, showing sicula. 



Figured Quart. Journ. Geol. Soc, 

 vol. lvi, p. 478, fig. 21 a. Stormer 

 Hall, Leintwardine ; Lower Ludlow 

 Shales. Coll. Wood. 



b. Distal thecse. Figured Quart. Journ. 



Geol. Soc, vol. lvi, p. 478, fig. 21 6. 

 Stormer Hall, Leintwardine ; Lower 

 Ludlow Shales. Coll. Wood. 



Monograptus irfonensis, Elles. 



PlateXLIII,fig.3. 



1900. Monograptus irfonensis, Elles, Quart. Journ. Geol. Soc, 

 vol. lvi, p. 407, fig. 19. 



Fig. 202.- 



-Monograptus irfonensis, 

 Elles. 



i 



Polypary very slender, approximately straight, 

 20 cm. or more in length, widening slowly to a maximum breadth of 1 mm. 

 Thecse eight to nine in 10 mm., of the general type of those of M. priodon, 



with about one-half of the thecal length 



involved in the hook, which occupies about 



one-third of the breadth of the polypary. 



Description. — The polypary is exceedingly long 



and slender, widening very slowly from a small 



sicula about 1 mm. in length to a maximum breadth 



of about 1 mm. 



The tliecaa show the characteristic ogee curva- 

 ture and hook-like apertural region of the M. priodon 

 type, but the whole theca is as it were more drawn 

 out and the isolation and retroversion of the aper- 

 tural region is less in proportion. 



Affinities. — Monog. irfonensis presents a certain 

 amount of resemblance to M. scanicus, but may be 

 distinguished by its straighter polypary, more defi- 

 nite ogee curvature of the thecse, and more conspicuous thecal hooks. 



Horizon and Localities. — Wenlock Shales (zone of Ct/rtog. Ijundgreni). 

 Wales : Left bank of R. Irfon, N. of Irfon Bridge, Builth. Shropshire : 

 Trewern Brook, near Middleton. Lake District : Harter Fell. 



Thecaj preserved as low cast. Enlarge- 

 ment of part of PI. XLIII, fig. 3. 



