O'Meaua — Report on the IrisJi Diatomaeecc. 379 



NavicuJa latissima, (Gregory). Marine. 



Yalve large, broadly elliptical ; ends slightly produced, rounded ; 

 intermediate free space broad, lanceolate, greatly expanded around tlie 

 central nodule ; striae linear, with moniliform striae interposed, conver- 

 gent in the middle, radiate towards the ends ; length '0060, breadth 

 •0032. (Plate 32, fig. 6.) 



Gregory, Q. J. M. S., 1856, p. 40, PI. v., fig. 4. Ealfs, in Pritch., 

 p: 903, PI. vii., fig. 70. Eab. PI. Em-. Alg., sect, i., p. 201. Donkin, 

 IS". H. Brit. Diat., p. 17, PL iii., fig. 2. — Pinnularia divaricata, 

 O'Meara, Q. J. M. S., 1867, p. 116, PI. v., fig. 7. 



Arran Islands, Stomachs of Ascichans, Ptoundstone Bay, Co. 

 Galway. 



NavicuJa meniscus, (Schumann). Presh water. 



Yalve broadly elliptical ; ends slightly produced, not capitate ; 

 intermediate free space narrow, except in the middle, where it 

 expands into a large stauroform band, wider towards the margin than 

 at the central nodule ; striae linear, with moniliform striae interposed, 

 convergent in the middle, radiate towards the ends ; length •0026, 

 breadth -0013. (Plate 32, fig. 7.) 



Schumann, Die Preussische Diat., p. 55, T. ii., fig. 32. Schumann's 

 account of the locality in which the form was found by him leaves 

 some doubt as to whether the deposit in which the form was discovered 

 was marine or fresh water; his words are: " In deposito Eegimon- 

 tano, in portu Pillawensi, in Mari Baltico. Lagersteclt, however, in- 

 cludes the form among fresh- water species, under the name of Navi- 

 cula punctata, var. asymmetrica, Sotvat. Diat. fi^an Spetsbergen, p. 29, 

 T. ii., fig. 7." This figure so precisely corresponds in all respects with 

 the form here described, as to render the identity perfectly certain. 

 Lagerstedt states that the frustule on front view is slightly unsymme- 

 trical on the longitudinal axis. This seems to me to have been acci- 

 dental, arising perhaps from the valves having been separated at one 

 end while adhering at the other; he adds, " only a single specimen of 

 this variety was ' found." And I have precisely the same report to 

 make. So distinct is tliis form in its leading characters that I consider 

 it a perfectly independent species, and not to be regarded as a variety 

 of ISTavicula punctata. 



Pond near the city of Armagh. 



Navicida lucida, IS". S. Marine. 



Yalve broadly elliptical, with sub-lanceolate ends; intermediate 

 free space lanceolate, narrow, except in the middle, where it expands 

 considerably ; a strongly marked submarginal sulcus is present ; 

 striae monilifoi-m ; puncta very close ; convergent in the middle ; 

 divergently radiate towards the apices ; length -0020 ; breadth -0012. 

 (Plate 32, fig. 8.) 



Stomachs of Ascidians, Eoundstone Bay, Co. Galway. 



H.I. A. PllOC, SEE. n., YOr-. II., SCIENCE. 2 T 



