I 



O'Meara — Report on the Irish DiatomacecB. 399 



kinii, Schmidt, Atlas, T. xii., fig. 64. This species is at first view 

 extremely like IS'avicula donkinii ; it is, however, considerably larger, 

 the striae finer and closer, and valve more deeply constricted. 



Arran Islands ; Stomachs of Ascidians, Broadhaven Bay, Co. Gal- 

 way. 



Navicula incurvafa, (Gregory). Marine. 



Valve slightly constricted ; median compartment tolerably wide, 

 •slightly inflexed at the ends, very slightly inflexed in the middle ; 

 compartments at either side about the same width as the median, 

 slightly arcuate, unstriate ; marginal band of striae narrow ; striae 

 nearly parallel throughout, fine, tolerably close ; indistinctly punctate ; 

 puncta very close ; length -0028, breadth '0009 ; at constriction, 

 •0008. (Plate 33, fig. 24.) 



Gregory, Q. J. M. S., 1856, p. 44, PI. v., fig. 13. In this figure 

 the marginal band of striae is represented as very much wider than it 

 appears to be in any of the very numerous specimens I have met with, 

 and also the compartments on either side of the median line are much 

 narrower ; in consequence of this, I was induced to consider the form 

 distinct from that of Gregory, and named it I^avicula pellucida, 

 Q. J. II. S., 1867, p. 115, PI. v., fig. 3. Ealfs, in Pritch., p. 893. 

 Donkin, IST. H. Brit. Diat., p. 49, PL vii., fig. 4. This figure does not 

 describe the incurved ends and middle of the median compartment. 

 Donkin regards the species as = to E^avicula interrupta, Grunow, Ver- 

 hand. der K. K. Zool. Bot. Gesell., Band x., 1860, p. 531, T. iii., fig. 20. 

 If so, Grunow' s figure is liable to the same remark as that of Gregory. 

 — I^avicula splendida, var. incurvata, Bab. Fl. Eur. Alg., sect, i., 

 p. 204. I think the form obviously distinct from E'avicula splen- 

 dida. 



Arran Islands ; Stomachs of Ascidians, Broadhaven Bay ; Sto- 

 machs of Ascidians, Eoundstone Bay, Co. Galway. Stomachs of Asci- 

 dians, Co. Clare. 



Navicula musca, (Gregory). Marine. 



Valve small, deeply and suddenly constricted ; ends sharp ; median 

 compartment relatively broad, inflexed at ends, slightly constricted in 

 the middle ; compartments at either side narrow, arcuate, unstriate ; 

 marginal band of striae narrow, obscurely punctate, extremely short in 

 the middle, radiate towards the ends; length -0012, breadth "0006 ; 

 at the constriction, -0004. (Plate 33, fig. 25.) 



Gregory, Diat. of Clyde, p. 479, PI. ix., fig. 6. This figure by no 

 means agrees with the description nor the measurements of the text. 

 So that it is not at all to be wondered at that Donkin should have con- 

 sidered it identical with that which he has figured as jSTavicula musca. 

 Donkin' s form referred to was properly regarded by Schmidt as a dis- 



