272 Notices of Memoirs — P. Macnair — 



middle of each valve. The abdominal segments which project from 

 behind the carapace have been considerably crushed. The three 

 caudal spines are well shown. They are of nearly equal length, 

 stout, fluted, and show traces of granulation on the riblets. Fig. 1, 

 which shows Dithjrocaris tricornis and D. testudinea, is after the 

 original drawing in Dr. Scolder's paper. 



The only other fossil preserved on the slabs containing the type- 

 specimens is a single specimen of Lingula mytiloides, which is seen 

 on the large slab with Dithyrocaris tricornis. As we shall presently 

 see, this is the commonest of all the fossils found in the Grallowhill 

 Limestone, in which it is often exceedingly numerous. 



The Gallowhill Limestone. 1 



About two years ago my attention was first directed to the peculiar 

 character of the limestone that forms the wall to the east of Gallow- 

 hill, near Paisley. The locality from which Scouler's type fossils 

 had been obtained had for a long time exercised my mind, as it had 

 done that of other local geologists, and when I first saw the limestone 

 of which the wall is built I was at once struck with its strong 

 similarity to that forming the matrix of the Scouler fossils. I took 

 a specimen of the limestone with me, and a comparison of it with 

 the specimens in the museum at once confirmed their identity. Both 

 present the same earthy-like appearance, their joint faces being lined 

 with calcite, and strongly charged with iron pyrites in nodular 

 masses and in strings and isolated cubes. Associated with the lime- 

 stone are bands of a much more argillaceous and sandy nature, of 

 which examples may be seen in the dykes and bings, the large 

 bing to the south of Gallowhill House having yielded numerous 

 examples of the different types of sedimentation that appear to have 

 prevailed upon this horizon. I am indebted to Mr. R. S. Houston 

 for the following analysis of the limestone, which, like the analysis 

 given in the Statistical Account, shows that it contains a large per- 

 centage of siliceous and clayey matter : 



Carbonate of lime . 

 Carbonate of magnesia 



Carbonate of iron . 



Alumina 



Siliceous matter (clay) 



Carbonaceous matter 



Moisture 



48-67 



•98 



5-70 



1-02 



40-23 



2-30 



•57 



99-47 

 After convincing myself of the lithological identity of the two 

 limestones I began to search for some evidence of a Phyllopod fauna, 

 and was soon rewarded by clear evidence of its presence. Nothing 

 to equal Scouler's specimens has yet been found, but fragments of 

 carapaces and tail spines are sufficiently numerous and in a similar 

 state of preservation to conclusively demonstrate the identity of the 



1 It should be clearly understood that the local term ' ' Gallowhill Limestone ' ' 

 used throughout this paper does not stand for any new limestone horizon, but 

 is only used to express a peculiar phase occurring at the top of the Blackbyre 

 Limestone. This, indeed, is the main object of the paper. 



