MONOGRAPTUS. 501 



Polypary somewhat irregularly curved, witli thecse on the convex or concave 



margin. Thecse four to two in 10 mm., perpendicularly placed, of 



approximately uniform width, and of a maximum length of 5 mm. 



equal to the width of the interspace ; apertural extremities very slightly 



reflexed. 



Description. — The polypary is only known in a fragmentary condition ; in what 



appears to be the proximal end the thecse are usually, though not invariably, on 



the convex margin and measure only 2 mm. in length, the interspace being also 



2 mm. in extent. Distal fragments, however, appear to be straight or to show 



slight concave curvature of the thecal margin. 



The thecge are very distant ; after the first they appear to be of approximately 

 the same length, and always equal to the width of the interspace ; they are set 

 perpendicularly, and show an unusual degree of uniformity in their width from 

 base to termination, which is often somewhat truncate in appearance, owing to the 

 very slight, but abrupt, reflexion of the apertural termination being turned away 

 and thus concealed from the observer. 



Affinities. — Fragments of Moriog. (R.) equidistans might be confounded perhaps 

 with 31. {R.) Linnxi, but the shape of the thecge is really distinct, and they are 

 much shorter. The variety originally separated by Lapworth as abbreviatus, 

 which occurs in the same beds, appears to be merely the proximal portion of the 

 same species. 



Horizon and Locality. — Grala-Tarannon (zones of M. turriculatus and M. 

 crispus). 



S. Scotland : Mount Beiiger ; Craigmichan Scaurs ; Grlenkiln Burn ; Meigle ; 

 Caddonhead ; Elwand Water, Melrose ; Waterfall at head of Dobb's Linn ; Clanyard 

 Bay, Drumore. Lake District : Spengill. 



Associates, etc. — Monog. (R.) equidistans is a somewhat rare fossil in the zone of 

 M. turriculatus, where it occurs associated with M. turriculatus, M. nudus and other 

 species. It has also recently been found in the Tarannon Shales in a boring in 

 Kent, where it occurs with If. crispus, M. exiguus, M. nodifer and M. Marri, an 

 association typical of the zone of M. crisqms. 



Collections. — Geological Survey of England and Wales, Sedgwick Museum, 

 Lapworth, and the Authors. 



