42 A. DE BREBISSON ON SOME FRENCH DIATOMACEiE. 



Biddulphia loevis Rop. Found at Divas (Cotes du Nord) at the 

 mouth of the Ranee, at a few leagues from St. Malo. It has also 

 been seen in the neighbourhood of Careutan. 



Epithemia succincta Breb. I discovered this Diatom in June, 

 1852, at Ouistreham, at the mouth of the canal, which was not 

 then open to navigation. It was growing mixed with Epith. sorex 

 and ventricosa, on the floating debris of senii-deconiposed Ulvacese. 

 I named it Epith. constricta, and I offered it, under that name, to 

 W. Smith, who was travelling through our country at that time. 

 Occupied at that time with the publication of the first volume of 

 his fine work on the English Diatomacese, he inserted Epithemia 

 constricta., and figured it in one of his supplementary plates. The 

 drawing was not made from my specimens, but from a different 

 plant of the same. Always seeking to avoid causes of error, I 

 have abandoned the name of constricta to Smith's species, and have 

 called the Ouistreham one Ep. succincta. It is much smaller than 

 the former ; its lateral indentation is also less decided. This 

 strangulation might be only accidental, and not furnish a really 

 distinctive character fit to establish a species. The Epithemia 

 gibberula, so common in the Mediterranean, sometimes presents a 

 kind of analogous indentation. 



M. Pedicino has figured this state of E. gibberula, figs. 10, 20, and 

 23 of plate 1 of his work on the Diatomaceaj of the thermal waters 

 of the Isle of Ischia. 



Note. — The preparations mentioned in the foregoing communi- 

 cation having been submitted to Mr. F. Kitton for his opinion, 

 elicited the following observations : — 



" I do not see much to add to M, de Brebisson's remarks. I 

 would suggest that the specific name of Navicula punctata be 

 changed, as we have already a Navicula punctulata. I should, 

 however, prefer retaining the genus Pinnularia, and referring to 

 that genus all forms with costate markings. The following are the 

 synonyms of this form : — Pinnularia tabellaria, Synopsis of 

 British Diatomaceee — the longer form of the same species, 

 P. acrosphceria of the same work. In a communication from 

 Dr. Arnott he says — ' I send you slide of P. tabellaria, true, from 



