98 BRITISH DIATOMAOEiE. 



lected in Cork Harbour were in a living state and in great abundance, and 

 from their length formed a conspicuous object even to the unassisted eye. 



Specimens sent me by M. De Brebisson are still larger than our native 

 forms. I have measured frustules from Brest "0318" in length, or nearly 

 twice as long as the Cork specimens. 



Professor Bailey has, as will be seen, constituted a new genus for the recep- 

 tion of this species ; but I think its general characters are sufficiently near 

 those of Synedra to permit its retention in that genus. 



60. Synedra deformis, n. sp. Frustules direct ; nodule obsolete ; 

 valve linear or linear-elliptical, suddenly constricted towards the 

 produced and often distorted extremities ; striae 36 in -001". 

 Length -0005" to -0008". Breadth of valve "0002". v.v. 



Fresh water. Lewes, Sussex, March 1853, W. Sm. 



61. Synedra investiens, n. sp. Frustules direct; nodule obsolete ; 

 valve linear, slightly attenuated towards the rounded extremities ; 

 striae 26 in -001". Length of F. -0005" to -0012". Breadth of V. 

 •00014". v.v. 



Marine : thickly covering an Ectocarpus. Kirkaldy, Fifeshire, March 1854, 

 Dr. Greville. 



62. Synedra tenera, n. sp. Frustules direct, clustered ; V. nearly 

 linear, or attenuated towards the slightly inflated extremities ; 

 nodule indefinite; strise 60 in -001". Length of F. -0022" to 

 •0066". Breadth of V. -00005" to *0002". v.v. 



Freshwater. Saltcoats, January 1854, Dr. Arnott. New Forest, September 

 1854 ; Lough Alloa, Co. Cork, June 1855; near Blarney and near Killaloe, 

 Co. Cork, July 1855, W.Sm. 



In outline not unlike S. delicatissima, with which it often occurs inter- 

 mixed, but it is a far smaller form and with more delicate strise. 



63. Gomphonema Naviculoides, n. sp. Stipes quite distinct and 

 regularly dichotomous ; F. V. nearly linear, truncate ; valves lan- 

 ceolate, acute ; nodule central ; extremities equal ; striae 30 in # 00l". 

 Length -0013" to -0025". v.v. 



Fresh water. Tank of Victoria Regia, Botanical Garden, Edinburgh, 

 August 1853, Dr. Greville. 



The valve of this interesting species is not to be distinguished from that of 



