Mr Traill on the Algce of the Firth of Forth. 171 



Description of Plate III. 

 Platyostomella Scotoburdigalensis. 



Fig. 1. An example seen from above, showing the deeply channelled suture 

 of the body whirl, and the single, equidistant, vertical colour-bands. Fig. la. 

 The same specimen, seen from the side. Craigkelly Quarry. 



Fig. 2. Another specimen, seen from above, in which the colour-bands are 

 arranged in pairs. Craigkelly Quarry. 



Fig. 3. A very small individual, in which the colour-bands are less in num- 

 ber and further apart. Craigkelly Quarry. 



Fig. 4. An example of the second variety, seen rather obliquely from the 

 side, with one transverse colour-band exposed to view. Craigkelly Quarry. 



Fig. 5. Another similar specimen, seen more from the side, and somewhat 

 from below, with two colour -bands visible. Craigkelly Quarry. 



Fig. 6. A further specimen of the vertically- banded variety, in which the 

 bands of colour are to some extent zig-zag. Craigkelly Quarry. 



Fig. 7. An example without colour-bands retained, seen from in-front, ex- 

 posing the mouth, with the reflected margins of the lips, and the straight, 

 strong, inner, or columellar lip. Fig. 7a. Another example, in which the 

 mouth is somewhat imperfect, but the reflection of the inner lip is well shown. 

 Craigkelly Quarry. 



Fig. 8. One of the original specimens fi'om the shale associated with the 

 ** Buckie-fake " of Raw Camps Quarry, near Midcalder, without colour-bands. 

 Fig. 8a. Mouth of the same. 



Fig. 9. A specimen in which the fine microscopic striae are seen to advan- 

 tage. Craigkelly Quarry. 



Naticopsis, sp. ind. 



Fig. 10. A specimen, seen from the back. Fifeness. 



Fig. 11. The largest example observed, showing the mouth, with its sharp 

 outer lip, and reflected inner lip. Fifeness. 



Fig. 12. Another and somewhat more elongated example. The short spire 

 is well seen in both Figs. 11 and 12. 



(The Figs. 1-9 are multiplied ten diameters; the size of Figs. 10-12 is 

 shown by the indicators. The whole of the originals are in the collection of 

 the Geological Survey of Scotland; those of Figs. 1-9 were collected by Mr 

 James Bennie; and those of Figs. 10-12 by the late Mr Richard Gibbs.) 



II. The Algce of the Firth of Forth. By George William 

 Traill, Esq. (Communicated by Professor Duns.) 



(Read 17th December 1879.) 



In submitting to the Koyal Physical Society of Edinburgh 

 the following list of the Algse of the Firth of Forth, I bear 

 in mind that the district has been worked in former years 

 by such distinguished naturalists and successful collectors as 



