16 38 Proceedings of the Royal Irish Aca'AemiJ. 



Surirella ovalis Breb. var. ovata (Kiitz.) V. H. — C, B ; L, mouth of Bunowen 

 River in brackish water, forms near var. crumena (Breb.), 33-34 x 

 21-22^. 



var. angusta (Kiitz.) V. H. — C. 

 var. minuta (Breb.) V. H. — C, 22-5 x 13^. 

 var. pinnata (W. Sm.j V. H— C, L, VL, M, IT, D, SL. 

 var. panduriformis (W. Sm.) W. West. — SL. 

 var. SUBMAMILLATA var. nov. — Var. cellulis late ellipticis 

 apicibus prodactis in mamillis brevibus. W, 38'5 x 16-5ju, 

 also 30 x 13/i and 29 x 125(11. 

 spiralis Kiitz. — B, L, W. 



robusta Ehrenb. (S. nobilis W. Sm.).— W, 2i6/i long ; SL ; M, 310 x 72^. 

 var. splendida (Ehrenb.) V.H.— W ; C, 205 x 76,u. 



Tribe Nitzschieae. 



Hantzschia amphioxys (Ehrenb.) Grun. — C. 

 Nitzschia curvula (Ehrenb.) W. Sm.— W. 

 *communis (Rabenh.) Grun. — B. 



**Clausii Hantzsch. — C, in a freshwater pool close to sea. 

 *dissipata Kiitz. var. acuta V.H. — 0, LG. 

 apiculata (Greg.) Grun. — C, 30-32 x 4-5-5^, in brackish water. 

 linearis (Ag.) W. Sm. — C, I, DL ; W, 74 x 9/x, girdle-face. 



var. tenuis Grun. — D. 

 sigmoidea (Ehr.) W. Sm.— D, 335 x 20-5^, girdle-view. 

 *obtusa W. Sm. — (JI; C, a form approaching var. scalpelliformis Grun., 

 92-5x6-6^; L. 



var. scalpelliformis Grun. — D. 

 var. brevissima Grun. — I, L. 

 **subtilis Grun. — D, 53^ long ; W, 74^i long ; SL, 60 x 4'5, valve-view. 



var. paleacea Grun. — C, 33/x long, 35 x 4*5 jx from another 

 place ; D, 46 x 2'8/x. 

 parvula W. Sm.— W. 



Palea (Kiitz.) W. Sm. — O, 57'5 x 5-5/x average; VL, L; D, 40 x 4-3^, 

 valve-view; W. 



var. debilis V. H.-C, L, W. 

 var. tenuirostris Grun. — C, 55 x 48^. 



var. fonticola Grun. — C, 18^ long; W, up to 28^ long, 

 ■i/n broad. 



