J. W. JUDD ON THE SECONDARY ROCKS OF SCOTLAND. 713 



ferruginous rock : in the latter they are in the condition of hollow 

 casts. Among the most common fossils here are Belemnites breviformis, 

 Ziet., Ammonites margaritatus, de Montf., A. Englehardti, D'Orb., 

 Pecten cequivalvis, Sow., P. sublaivis, Phil., and P. liasinns, Nyst, 

 Gryphcea cymbium, Lam., and G. gigantea, Lam., Rhynchonella 

 tetrahedra, Sow., and JR. acuta, Sow., Spiriferina Walcotti, Sow. sp., 

 and S. rostrata, Schloth. sp. ; but nearly all the well-known forms of 

 the English Middle Lias may be found by a diligent collector of the 

 fossils, together with a few species which appear to be peculiar to 

 this area. Some of the beds appear to be almost made up of the 

 shells of Gryphcea and Pecten, while calcareous concretions, crowded 

 with Bhynchonellce, are very common. 



The underlying argillaceous beds (the Pabba Shales) are not so 

 well exposed in the cliff- section, owing to the foundering of masses 

 of the superincumbent harder beds. At the Moor of Hallaig, how- 

 ever, these micaceous clays cover a considerable area, and are tra- 

 versed by innumerable dykes of basalt. These having been in many 

 cases removed by atmospheric disintegration, have caused the moor 

 to be furrowed in all directions by a series of deep trenches, which 

 prove very dangerous to the unwary traveller. In the sides of these 

 trenches, and in the watercourses, numerous fossils of the Pabba 

 Shales can be found ; and a list of the species from this district has 

 been given by Professor Tate (see Quart. Journ. Geol. Soc. vol. xxix. 

 p. 342). Both Ammonites Jamesoni, Sow., and its accompanying species, 

 and A. armatus, Sow., with the forms usually associated with it, occur 

 at Hallaig. The species of fossils and characters of the beds are iden- 

 tical with those seen at the island of Pabba. 



At several other points in Eaasay strata of Middle-Lias age may 

 be detected. Thus, near Suishnish Point the Pabba Shales are seen 

 traversed by numerous trap-dykes. Here fossils are numerous, and 

 of the same species as at Hallaig and Pabba. Among the most 

 numerous forms were Belemnites paxillosus, Schloth., Ammonites 

 brevispina, Sow. (sometimes of large size), Gryphcea obliqua, Sow., 

 Pecten cequivalvis, Sow., P. sublcevis, Phil., and P. liasinus, Nyst, 

 Pinna folium, Y. & B., Hippopodium ponderosum,8ow., axi&Avicula 

 incequivalvis, Sow. 



The existence of inland developments of the Pabba strata is indi- 

 cated by the characteristic fossils which are sometimes found ; but 

 no useful sections occur at points other than those already referred 

 to in the island of Eaasay. The exposure of the Scalpa beds in the 

 great cliffs between Fearns and Leac is particularly fine ; but, on 

 account of the inaccessibility of the cliffs, a good continuous section 

 cannot be obtained. 



The manner in which, owing to the action of a great fault, the 

 Scalpa beds are found lying against the Torridon Sandstones in the 

 island of Scalpa, has been already illustrated (see page 673, fig. 4). 

 The upper part of the Lias series here abounds with fossils, which, 

 however, are not very well preserved. Owing to the residence for 

 some time in this island of a former student of the Eoyal School of 

 Mines (Mr. A. Grant), I was enabled to obtain a considerable number 



