MONOGRAPTUS. 



411 



Ijal-e District : Southwaito Wood ; Austwick Beck ; W. side Long Sleddale, etc. 

 Wales: Benartli Shore, Conway ; Rose Mill Farm, Conway ; Pencerrig ; Trecoed, 

 near Builtli; R. Irfon, near Builtli ; Corwen ; Ruthin Road, nr. Llangollen; 

 Tarannon District. Scotland : Riccarton. 



Associates, etc. — Monog. vomeriiius is a common fossil throughout the Weiilock 

 Shales ; it seems to make its first appearance in their passage beds below, but is 

 especially abundant in the Lower Wenlock Beds, where it occurs associated with 

 Cijrto(j. 3Iiirc]iisoiii, Moiiog, priodon, (JIadioy. Geinitziaiins, and other forms. At 

 higher horizons it may he found with any of the zone fossils, and with M. 

 FlemiiKjii and ]\[. dtihiits. 



Collections. — Sedgwick Museum, Lapworth, and 

 the Authors, etc. 



Pigs. 276 a and b. — Mo»oijraptus vomc 

 rinus, var. basilicus (Lapworth). 



^ff 



'/' 



a. Proximal end. Enlargement of part 

 of PI. XLI, fig. 2 d. 



h. Adult thecoe, showing different ap- 

 pearances presented according to 

 varying compression. Enlargement 

 of part of PI. XLI, fig. 2 c. 



Var. basilicus, Lapworth. Plate XLI, figs. 2 a — d. 



1880. Monoijraidus ijalaensis var. basilicus, Lapworth, Ann. 

 Mag. Nat. Hist. [5], vol. v, p. 152, pi. iv, figs. G a, 6 b. 



In var. basilicas the polypary is far stouter than 

 in M. vouierinus, attaining a breadth of at least 3 

 mm., and occasionally even more. The thecse are 

 very similar in form to those of M. conierhius, but 

 overlap for fully two-thirds of their length. 



Horizon and Localities. — Wenlock Shales (zones 

 of Gtjrtoij. Marcliisoni to Gijrtog. Linnarssoni). 



Wales : Pencerrig, Builtli, Builtli Road, etc. 



Var. basilicas is fairly common in the Lower 

 Wenlock Shales of the Builth area, where it occurs 

 associated Avitli Gijrtoij. Marchisoiii, Moii-og. priodon, 

 M. voDieriiias, M. riccartonensis, Cijrtoij. Linnarssoni, 

 and other forms. 



Collections. — Lapworth and the Authors. 



Var. gracilis, var. nov. Plate XLI, figs. 3 a — d. 



1900. Monorjrai)tas vomeriiias, var. (I, EUos, Quart. Jouni. Geol. Soc, p. 405, fig. 16. 



Var. gracilis differs from M. vomerinus in having the whole proximal portion 

 gracefully recurved ; the polypary also widens more gradually, and its width rarely 



