14 KITTONj ON DIATOMACE^. 



cured from Dredgings." In the following observations I 

 have assumed the amplification in the first pa^jer to be the 

 same as that in the second, viz., 600 diameters. 



The fi)llowing forms, described in the Rev. E. O'Meara's 

 papers (Vol. VII.), may, I think, be referred to previously 

 described species. 



Navicula pellucida, O'M., fig. 2, is a state of N. Pandura 

 of De Brebisson. 



Navicula IVrightii, O'M., fig. 4. is certainly only N. clavata 

 of W. Gregory ; the striae next the median line being obli- 

 terated by abrasion. 



Navicula amplioroides, O'M., fig. 3, seems to be an 

 Amphora resembling A. salina of the Synopsis (= A. proteus 

 of AV. Gregory). Query, is not the nodule a small grain of 

 quartz ? 



Pimmlaria constricta, O'M., fig. 8, possibly a form of 

 Navicula truncata, a very variable species both in size and 

 costae. 



Pimmlaria divaricata, O'M., fig. 7, if correctly figured and 

 described, can be neither a Pinnularia nor Navicula, as none 

 of these genera have forked strise or costse. 



Surirella pulchella and g)'acilis* O'M., figs. 10 and 11, are 

 only forms of S. lata of the SynojDsis, and this is merely a 

 variety of that most variable form S. fastuosa. In a good 

 gathering of this species, S. pulchella, S. gracilis, S. lata, 

 may all be detected, and probably a dozen other species if 

 slight diiferences in size, outline, or striation, constitute new 

 species. Dr. Greville, in ' Trans, of Mic. Soc.,' 1862, p. 19, 

 makes the only difference between S. lata and S. fastuosa 

 to consist in the form of the median space ; but an examina- 

 tion of numerous specimens j^roves that his only character is 

 of no value, for in specimens from the same locality all forms 

 of the median space aj^pear. Dr. Gregory projDOsed uniting 

 his Campylodiscus sinmlans with S. fastuosa, but the former 

 is a true Campylodiscus having the poles of the opposite 

 valves at right angles to each other (a feature not peculiar to 

 C. simulans or C. bicruciatus, in the Campylodisci tlie opposite 

 valves of the frustule are always in that position). C. bicru- 

 ciatus is only a frustule of C. simulans, and the latter is only 

 a large variety of C parvulus. 



Coscinodiscus fasciculatus, O'M., fig. 1, Vol VII, is an 



* Herr Grunow describes and G^ures aS. gracilis. The following are liis 

 specific cliaracters : — " S. gracilis in (= TryblioncUa gracilis, W. Smith ? ?) 

 Mittelgross, Sclialen breit linear mit abgerundeten oder conisclien Enden, 

 Rippen 12 — 14- im O'OOl Im siisswasser." ' Verhand. der k.k. zoo.-bot. 

 Gesellschaft in Wien,' Band 12, s. 450, u. , Taf. vii, fig. 11. 



