MONOGRAPTUS. 



431 



Near Gill, Cautley. S.Scotland: Moss Peeble Burn; Ewes Water, 6 miles N. 

 Langholm; Kirkstile Burn, 4| miles N. by W. of Langholm. 



Associates, etc. — Monog. flexilis is sometimes fairly abundant in the /one of 

 Gyrtog. Linnarssoni occurring in association with the zone fossil, Monog. vomerinus 

 and var. basilicus and M, duhius', in the Lake District it has been found by Misses 

 Watney and Welch with a fauna which appears to us to be characteristic of the same 

 horizon. 



Collections. — Geological Survey of Scotland, British Museum (Natural History), 

 Watney and Welch, and Elles. 



Fig. 291. — -Monograptus acus, Lapworth 



Monograptus acus, Lapworth MS. Plate XLIII, tigs. 7 a — c. 



1882. Monograptus acus, Lapworth (name only), Quart. Journ. Geol. Soc, vol. xxxviii, p. 660. 



Polypary very long and flexed, 16 cm. or more in length, having an average 

 breadth of 2 mm. Theeae eight in 10 mm. of the type of those of M.ILilli, 

 but smaller and with rather less eversion and overlap. 



Description. — The polypary is remarkably flexed; 

 the thecas in the proximal portion are on the convex 

 margin, while those of the distal region are on the 

 concave side. The breadth is commonly uniform 

 for the greater part of the length of the polypary, 

 but a widening from 1 mm. to 2 mm. takes place 

 rather gradually in the proximal portion. 



The thecse are of the type of the distal thecas of 

 M. Halli, though the very slight retroversion of the 

 apertural region brings them very near in appear- 

 ance to some of the members of the concoluttis group. 

 Affinities. — Monog. acus agrees with M. Halli in 

 the general type of its theeae, but differs in the 

 curvature of the polypary and the smaller, less 

 everted thecas. It seems to be identical with the 

 form called by Nicholson M. brought-onensis in the 

 paper on the Stockdale Shales by himself and Marr, 

 but never described. 

 Horizon and Localities. — Gala-Tarannon Beds (zone of M. crispus). 

 S. Scotland: Grieston Quarry; Meigle Quarry; Tushielaw. Lake District: 

 Knock, Edenside ; Broughton Moor (?).. 



Associates, etc. — Monog. acus occurs associated with M. galaensis, etc., in Meigle 

 Quarry. 



Collections. — Sedgwick Museum, Marr, and Lapworth. 



57 



Thecoe in partial low relief. Enlarge 

 ment of part of PI. XLIII, fig. 7 a. 



