16 30 Proceedings of the Royal Irish Academy. 



*Cocconema laevis (Nag.) W. West. — C, B ; W, 24 x 5-6/t. 

 lanceolatum Ehrenb. — C, 79 x 13 3/z; W. 



*leptoceras (Kiitz.) W. West var. elongata (V. H.) W. West. — C. 

 *mierocephala (Grun.) W. West. — C, D. 

 *obtusum (Greg.) W. & G. S. West.— M, C. 

 tumidum Breb. — C. 

 turgidum (Greg.) W. West. — W. 



ventricosum (Ag.) W. & G. S. West. — IT ; C, up to 33 x 8 - 3/x, valve-view ; 

 SL; nearLG; OP, 28-3x7-5, valve- view; D, 20x7-5/*; Croaghmore 

 cliffs. 



Tribe Naviculeae. 



Mastogloia Smithii Thw. — C, 48 - 5 x 1 2/x, in several places ; W. 



var. amphicephala Grun. — C, SL; near LG. 

 Stauroneis anceps Ehrenb. — C, 40 x 8'6/< ; L; W, 49 xl3 - 3^, a broad form; 

 D, Croaghmore cliffs. 



var. LATA, var. nov. — Var. cellulis diametro 3-plo longioribus, 

 60 x 20/*. A marked variety, as the type is 4J times as 

 long as broad. C. 

 var. linearis (Kiitz.) V.H.— L ; W, 46 x 12/*. 

 var. amphicephala (Kiitz.) V.H. — W, 45 x 9/* ; C, 51 x 10/*. 

 Phoenicenteron (Nitzsch.) Ehrenb.— C, up to 152 x 28-4/* ; L ; W.121 x 28/*, 

 in one locality all small forms 86-95x20/*; M, 180-183/* X 

 31-33/*. 



f. PRODTJCTA, f . nova. — F. cellulis minoribus et apicibus distincte 

 productis, 81 x 18'2/x average size, some only 73 x 15//. C. 

 gracilis Ehrenb. — W. 

 acuta W. Sm. — M, I, C ; D, small forms 80-90/* x 13-14/* ; W, average 



size 110 x 17-5/t. 

 Legumen Ehrenb. — W. 

 Navicula acuminata W. Sm. — W. 

 *affinis Ehrenb.— IT. 

 alpina (W. Sm.) Ralfs.— CP, SL. 

 ambigua Ehrenb. — W, 59 x 13/*. 

 amphirhyncus Ehrenb. — W. 

 amphisbaena Bory.— C, W ; D, 55-62 x 21-23-4/*. 

 *anglica Ealfs.— D, C, W. 

 *appendiculata Kiitz. — L ; W, 41 x 6-6/* ; M. 

 **atomoides Grun. — B. 



