Dr. Greville on a new species of Spiridens. 325 



The freshwater Mussel [Mya margaritifera, L.) is abundant 

 in both the Dee and Don. The specimens in whose intestines 

 the following Diatomacea. occurred, were from the former river 

 eighteen miles inland. 



MeridiecB. Achnanthece. 



Meridioii circulare, Ag. Achnanthes minutissima, Ehr. 



FragilariecE. Cymbellecs. 



Fragilaria hyemalis, Lyngb. Cymbella flexella, Kiitz. 



Diatoma flocculosum, Ag. C. leptoceras, Kutz. ? 



D. tenue Aq. Cocconema cymbiforme, Lhr. 



Meloseirea. GomphonemeeB. 



Meloseira distans, Kiilz. 1 Gomphonema geminatum, Ag. 



G. pohliaeforme, Kiitz. 



Surirelleee. G. minutum, Ag. 



Synedra capitata, Ehr. Namculece. 



' ' Navicula rhomboides, Ehr. 1 



CocconoidecE. N. cuspidata, Kutz. 



Cocconeis Pediculus, Ehr. N. viridis, Kiitz. 



Intermixed with these were spiculse of Spongilla. Generally 

 speaking the individuals of each species were of the minimum 

 size, certainly far less than that usually attained. Of those 

 brought within the sphere of the currents produced by the cilia, 

 the smaller alone Avere swallowed. Of the species enumerated I 

 have found the following on our mountains at heights varying 

 from 2800 to 3800 feet : viz. Meridion circulare, Diatoma floccu- 

 losum, D. tenue, Meloseira distans ?, Gomphonema pohliceforme, 

 G. minutum, Navicula rhomboides ? and N. viridis. The Meloseira 

 I have found to constitute a considerable proportion of the fine 

 black mud found beneath patches of snow on Ben-na-Muich 

 Dhu. 



XXXIV. — Notice of a new species of Spiridens. 

 By R. K. Greville, LL.D. &c.* 



[With a Plate.] 



The genus Spiridens, established by Nees von Esenbeck in the 

 1 1th volume of the 'Nova Acta Acad. Caes. Leopold. Car. Na- 

 turse Curiosorum,' has hitherto contained the single species it 

 was constituted to receive, viz. Spiridens Reinwardtii. This most 

 noble of all mosses, as it is justly designated by Sir W. J. Hooker, 

 is a native of the Molucca Isles ; twelve inches or more in height, 

 with a robust, Bartramia-like habit. It is figured in the Trans- 

 actions above-mentioned ; but the British botanist will also find 

 a figure and description in the first volume of Sir W. J. Hooker's 

 * Botanical Miscellany,' published in 1830. 



* Read before the Botanical Society of Edinburgh, Mavcb 9, 1848. 



