124 Rev. W. Smith on Deposits of Diatomaceous Earth. 



as an acute observer in another department of natural history is 

 not unknown to the readers of the ' Annals '), is a large and hand- 

 some species intermediate between E. zebra and E. granulata, 

 but distinguished from both by its stouter habit, the regular 

 convexity of its dorsal outline, and its rounded ends. I add a 

 description in a note*. 



fEpithemia Musculus. 



\ zebra. 



f ocellata. 



t gibba. 



T turgida. 



granulata. 



Hyndmanii. 





fHimantidium pectinale. 



Fragilaria virescens. 



capucina. 



fCyclotella operculata. 



minutula. 



fMelosira orichalcea. 

 f arenaria. 



Campylodiscus noricus. 



Surirella splendida. 



t bifrons. 



-f Solea. 



t elliptica. _;oIo3S 



fSynedra capitata. 



t biceps /3. recta. 



f ulna. 



sigmoidea. 



fCocconeis Pediculus. 

 -f Cymbella Ehrenbergii. 



cuspidata. 



•fCocconema lanceolata. 



fCocconema Cistula. 

 'fGomphonema acuminatum, 

 t constrictum. 



geminatum. 



fNavicula nobilis. 



t major. 



f viridis. 



f sphserophora. 



f radiosa. 



nodosa /3. striata. 



binodis. 



lata. 



dicephala. 



mesolepta. 



t elliptica. 



firma. 



f attenuata. 



fStauroneis Phoenicentron. 



punctata. 



lanceolata. 



cardinalis. 



t lineolata. 



amphicephala. 



Platystoma. 



t Amphora ovahs. 



Tabellaria fenestrata. 



ventricosa. 



•f cymbiformis. 



It is evident from the above that neither of the deposits found 

 can with strictness be termed fossil ; that they are simply the 

 siliceous coverings of species, the greater number, if not all, of 

 which, still inhabit the waters of the lake, having required no 

 doubt a lengthened period for their accumulation, but still one 

 comparatively recent, and which cannot be regarded as conferring 

 a fossiliferous character on the deposit itself. 



In the ' Magazine of Nat. Hist/ for July 1839, an interesting 

 description of an " Infusorial " earth found on draining Lough 

 Island- Reavey, co. Down — is given by Dr. Drummond of Bel- 

 fast : I have been enabled by the kindness of W. Thompson, Esq. 

 of that town to compare this deposit with those I have here 

 noticed. Although occurring under very similar circumstances, 



* Epithemia Hyndmanii, W. Sm. E. major, a latere secundario valde 

 et sequaliter convexa, apicibus obtusissimis rotundatis non recurvatis, striis 

 transversalibus moniliformibus vix convergentibus : a latere primario ob- 

 longa medio valde dilatata. Long, ^^^-tt^ unciae. 



