part 4] THE UPPER OEDOVICIAN OF THE BEBWYX HILLS. 497 



beds are nearly vertical, and thus fairly accurate measurements of 

 the thicknesses are easily obtained. 



On leaving the watershed the bridle-path, which follows the 

 stream, runs obliquely across the strike. The beds which are 

 exposed here (<>D, fig. 3) are about 400 feet above the base of 

 the Ashgillian, and from this point the beds are highly fossili- 

 ferous for another 100 feet, the most striking feature being the 

 presence of numerous forms of bryozoa, particularly : — ■ 



Monticulipora fibrosa M'Coy. 

 Monticulipora lycoperdon (Say). 



Other fossils from this horizon are 



Pleurocystis rugeri Salter. 



Christiania tenuicincta (M'Coy). 



Leptsena sp. 



Orthis sp. a. [See p. 507.] 



Orthis. 



Stropheodonta corrugatella (Davidson). 



Agnostus agnostiformis (M'Coy). 



Cybele rugosa var. attenuata Reed. 



Gheirurus juvenis Salter. 



Ptilodictya dichotoma Portlock. 

 Phyllopora sp. 



Illsenus bowmanii Salter. 



Illienus sp. 



Lichas laxatus M'Coy. 



Phillipsinella parabola (Barrande). 



Pterygometopus sp. 



ProetusC?). 



Bemopleurides nicholsoni Reed 



(common). 

 Trinucleus sp. 



The rock which constitutes this horizon is a slightly sandy grey- 

 blue mudstone, which weathers to a greenish-grey or buff colour 

 The fossils weather out as casts rilled with brown rottenstone. 



About the turn of the path where two small valleys meet to run 

 nearly due south, the beds begin to take on a more massive nature, 

 and to become rather more arenaceous ; but they always remain 

 essentially mudstones, owing to the extremely fine grain of the 

 sand-particles. In colour they are the same as the underlying 

 beds. Fossils are usually plentiful and well preserved. One 

 excellent locality was found on Craig Fawr (\8, fig. 3), where 

 several complete specimens of Calymene have been obtained. 

 Other localities (213, I A, c2, o 3) are shown on the map (fig. 3). 

 At all these localities the fossils seem to be similar, the most 

 characteristic forms being Calymene quadrata sp. nov. and large 

 Christiania tenuicincta. The following is a list of the forms 

 found at the above-mentioned localities, and others situated in 

 the same stratigraphical position : — 



Atrypa cf. marginalis Dalman. 

 Cliristiania tenuicincta (M'Coy) ; large 



rotund form. 

 Do. do. ; elongate form. 

 Leptsena rhomboidalis var. y Reed. 

 Meristina cf. crassa (Sowerby) ; one 



specimen. 

 Orthis calligram/ma Dalman. 

 Orthis sp. a. [See p. 507.] 

 Plectambonites sericea, type. 

 Plectambonites aft. rhombica (Davidson). 

 Plectambonites sp. nov. 

 Rafinesquina subarachnoidea Reed. 

 Strophomena sp. 



Calymene quadrata sp.noy. [Seep. 504.] 

 Cybele loveni Linnd. 

 JU&nus. 



Lichas geilcei var. nov. [See p. 505.] 



Lichas sp. 



Pterygometopus brongniarti var. 



nov. [See p. 506.] 

 Remopleurides nicholsoni Reed. 

 Sphserocoryphe thorn son i Reed. 

 Staurocephalus cf. murchisoni 



Barrande. 

 Stygina latifrons? (Portlock). 

 Trinucleus cf. bucliandi Barrande. 

 Phyllopora. 



Ptilodictya dichotoma Portlock. 

 Monticulipora fibrosa M'Coy. 

 Connlaria planiseptata Slater. 

 Conradella cf. fimbriuta Ulrich A: 



Schofield. 

 Orthoceras sp 



