250 A. A. C. ELIOT MERLIN ON NAVICDLA SMITHII AND N. CRABRO. 



piercing the capped " pearls." The specimens examined are also 

 from the Gulf of Naples, some showing the composite structure 

 well, while in other equally large forms the primaries are so 

 small that the secondaries cannot be properly resolved, although 

 one can see that they are there. The N". crabro is figured in 

 Yan Heurck's Atlas of the Diatom aceae, Plate IX. fig. 1, and 

 a description of it is given on page 89 of the text. Only the two 

 rows of " pearls " are mentioned as its distinguishing feature, the 

 minuter secondaries having evidently escaped notice, as in the 

 case of ]\ r . Smithii, unless, indeed, it should prove that the Belgian 

 varieties of both species are very different in their ultimate 

 structure from those obtained in the Mediterranean, although 

 similar in other respects. 



Journ. Qut)i-cti Microscopical Club, Ser. 2, Vol. X., No. 62, April 1908. 



