PalcBOZoic Bivalved Entomostraca. 397 



Wigtonshire, 1873, p. 34) as having been found (about 1872) 

 in the soft grey micaceous mudstone (weathering rusty) of 

 the hillside opposite Blair Farm, about 8^ miles north-east of 

 Girvan, and as having an analogue in some better-preserved 

 specimens from the Pentland Hills. In the Girvan specimen, 

 which is in the collection of the Geological Survey of Scot- 

 land, and marked ' M. 1920,' an apical depression, not quite 

 central, is continued a little way on the longer axis of the 

 cast by a tapering furrow. Studied in the light given by 

 some other Entomids, this appears to me to be the cast of a 

 valve of a very globose Entomis, and that it has been 

 squeezed from end to end, so that the long and short axes 

 have been mutually interchanged. The better specimens 

 are considered as typical of a new species, Entomis ghhuhsay 

 This is again figured here as fig. 12. 



It belongs to the Upper- Silurian stage both in Ayrshire 

 and the Pentland Hills. 



II. The late Mr. G. C. Haswell, of Edinburgh, submitted 

 for examination, in 1866, two somewhat similar but larger 

 specimens, from the Upper-Silurian mudstoncs of the Pent- 

 land Hills. 



1. Fig. 13. One of these specimens had a suboval base, 

 somewhat more boldly curved on one side than on the other 

 and a conical elevation with unequal slo|)es, the apex beino- 

 nearer one end of the longer axis than the other. Size : 

 length -1%, breadth i%, height i\ inch. There is no apical 

 depression ; the edge all round was evidently compressed so 

 as to present a vertical rim (narrower and more inturned 

 apparently where partially buried in the matrix on the flatter 

 side), representing the cast of the inside of a flange, set on 

 nearly at right angles within the margin, to receive the opposite 

 edge of a corresponding valve, as on the ventral margin of 

 Leperditia (see Ann. & Mag. Nat. Hist. ser. 2, vol. xvii. 

 pi. vi. fig. 4 c). The conical condition may be the result of 

 pressure, which has obliterated the umbilical spot. 



2. The second analogous specimen (figs. ll«-lle) from 

 the Pentland Hills was a somewhat similar cast, nearly hemi- 

 spherical, with a slightly oval base-line, and vertically rimmed 

 all round, but not so deeply and uniformly as in the specimen 

 last described ; nor was the margin quite even on one plane • 

 for the middle of one moiety had a slight extension, A 

 marked line (transverse to the longer axis of the fossil) passes 

 from this median projection, over the cast, to the central or 

 umbilical depression, and is continued, as a definite furrow 

 to the opposite margin, where it widens, making the vertical 

 rim locally more distinct. The apical depression has a smooth, 



