CONTAINING DIATOMACEOUS EXUVIiE. 



described forms, most of which are very interesting. Such is 

 a general account of the results obtained ; and after these pre- 

 liminary remarks I shall now proceed to the details. I shall 

 first give the list of known species, under the two heads of 

 marine and fresh-water forms, as Mr. Roper has done in the 

 case of the Thames mud ; and I shall then briefly describe the 

 new species, which will also be figured. But as circumstances 

 have rendered it impossible for me to have more than one 

 plate in the present number of the * Journal,' I am compelled 

 to reserve one-half of the figures till the next number. 



It is proper to explain that I shall have to mention several 

 new a forms, as occurring in this deposit, which I do not figure, 

 although no figures have as yet appeared of them. The reason 

 is, that these forms have been recently observed by others, 

 prior to me, and it is to be presumed that the first observers 

 will take an early opportunity of describing and figuring 

 them. I propose to figure all such forms as are now, for the 

 first time, distinguished by myself, and also some striking 

 varieties of known species, in which the Glenshira deposit is 

 uncommonly rich. Without further preamble, let us now 

 proceed to the list of known forms. 



I. Marine Species, 



including such as occur in both sea water and brackish water, 

 as well as those which seem to belong to brackish water more 

 especially : — 



1. Epithemia Mnsculus. 



2. Amphora affinis. 



3. 



,, tenera. 



21. 



?> 



vitrea. 



4. 



„ costata. 



22. 



Amphipleura sigmoidea. 



5. 



Cocconeis Scutellum. 



23. 



Navicula Liber. 



6. 



„ Grevillii. 



24. 



jj 



Smithii.* 



7. 



Coscinodiscus radiatus. 



25. 



?' 



Jenneri. 



8. 



„ excen tricus. 



26. 



>> 



convexa. 



9. 



Eupodiscus crassus. 



27. 



jj 



elegans. 



10. 



„ Ralfsii. 



28. 



•>•> 



palpebralis. 



11. 



Campylodiscus parvulus. 



29. 



V 



punctulata. 



12. 



Surirella fastuosa. 



30. 



» 



pusilla. 



13. 



„ constricta. 



31. 



)> 



Didyma. 



14. 



Tryblionella punctata. 



32. 



» 



nitida.f 



15. 



„ acuminata. 



33. 



» 



granulata, Breb 



16. 



Nitzschia Sigma. 



34. 



Pinnularia directa. 



17. 



„ angularis. 



35. 



j> 



Cyprinus. 



18. 



„ birostrata. 



36. 



)> 



peregrina. 



19. Amphiprora alata. 



20. ,, constricta. 



* N. elliptica, W. Sm. M. de Brebisson has given this name, on account 

 of the term ' elliptica ' having been long applied to another species by 

 continental writers. 



f This is a beautiful new species, to be figured iu vol. ii. of Mr. 

 Smith's ' Synopsis.' 



% Also a very fine new form. Prof. Arnott finds it in the Clyde. 



