MONOGRAPTUS. 177 



Monograptus proteus (Barrande). Plate XLVIII, figs. 8 a — c. 



1850. Graptolithus proteus, Barrande, Grapt. de Boheme, p. 58, pi. iv, figs. 12 — 14. 

 1890. Monograptus proteus, Geinitz, Grapt. Dresden Museum, p. 21, pi. a, fig. 28. 

 1892. Monograptus proteus, Tornquist, Siljausomrad. Grapt., ii. p. 40, pi. iii, figs. 29, 30. 

 1897. Monograptus proteus, Peruer, Grapt. de Boht'ine, p. 14, pi. 22, figs. 21 — 23. 

 1899. Monograptus proteus, Tornquist, Monograptidse of Scanian Bastrites beds, p. 23, pi. iv, figs. 

 23—24. 



Polypary coiled into a helicoid spiral, with long and extremely slender proximal 

 portion and fairly robust distal portion. Thecas seven to ten in 10 mm., of 

 uniform type, triangular, in contact only, with barbed apertural regions, 

 in which only one-third of the free part is involved ; those of the proximal 

 portion of the polypary more distant and more slender than those of the 

 distal portion. 

 Description. — The polypary rarely shows the whole of the slender proximal 

 end, but when this is complete it is seen to widen very gradually at first and then 



somewhat more rapidly, for in its distal portions the 

 a ~(BM^ande). aP hS P ' C P°lyP ar y ™ fairly robust; fragments of this part 



are of far commoner occurrence than those of the 

 initial extremity. 



In the most characteristic form of the polypary 

 the thecge are all on the outer side of the curve, and 

 therefore symmetrically arranged, but this is not a 

 constant feature. The proximal thecas are all 

 extremely slender, with, distinct though small barbed 

 « b c apertural regions. The gradual change in the form 



a. Proximal portion, showing form of e ,t , i -i , i -i • , -i -\ i i i 



thecffi. Gein-dywyii stream, Lian- °i the tnecas towards the distal end can best be seen 



Kvnmair ; Erynmair Beds.' Coll. , Jy comparmg figg> 3 32 ft _ c . 



h ' S1 S y H w e i di 1 al the f *' in f lm i Affinities.— -The helicoid (conical) spiral of Monog. 



relief, showing form of apertural •'•' \ / I ./ 



margins Enlargement of part of pro t ms combined with the arrangement and form 



PL XLVIII, fig. 8 c. ' ° 



c. Distal theca; of same specimen, in low f the thecaa, renders the species easy to separate 



from all others. 



Horizon and Localities. — Llandovery-Tarannon Beds (zone of M. convolutus, to 

 zone of M. crispus). 



S. Scotland: Dobb's Linn ; Belcraig; Duff kinnell; Mount Benger; Grieston ; 

 Broad Meadows, etc. Wales: Bout Dolgadfan, Llanbrynmair ; Gelli-dywyll 

 Stream, Llanbrynmair, etc. Lake District: Browgill. Ireland: Portaferry, Co. 

 Down. 



Associates, etc. — Monog. proteus is not uncommon in the beds of the Upper 

 Birkhill Shales and Lower Gala and their equivalents. It occurs in the zone of 

 M. convolutus, associated with M. convolutus, M. Clingani, M. liniatuhis, M. lobiferus. 



