4 DR. GREGORY, ON SOME NEW SPECIES 



but only as the forms figured under the names here given by 

 Ehrenberg and Kiitzing. It is indeed probable that Pinnularia 

 megaloptera is only a long form of P. costata (lata, Sm.) ; and 

 that JV. duhia may be a variety, as some believe, of Njirma, 

 although I am rather inclined to think that N. ampliigomphus, 

 Elir. and N. dilatata, Ehr., both of which occur in Lochleven 

 with N. duhia, may be forms of one species with the latter, 

 but distinct from N. jirma. For this reason, I have only 

 mentioned N. duhia in my list. The remarkable form which 

 I have referred to N. Bacillum, Ehr, is perhaps, as I find from 

 Ehrenberg's ' Microgeologie,' rather his N. Americana, al- 

 though, to judge from his figures, these two form but one 

 species. It is also probable Xhdit Pinnularia Dactylus is only a 

 variety of P. major. 



II. MS, species ; named by Prof, Smith, but unpublished. 



13. Navicula apiculata, Sm, — Mull earth, Elgin, Dhu Loch, 

 in Glenshire. 



14. iV, rostratay Sm. — Near Haddington, Lochleven ; near 

 Oban, Linlithgowshire, Dhu Loch in Glenshira, Elgin ; also 

 recently near Hamilton, and at Borthwick Castle. 



15. JV. scutelloides, Sm. — Norfolk, Lochleven. 



16. Mastogloia Grevillei (for the locality only), Lochleven.* 



At one time I regarded Navicula scutelloides as one of the 

 innumerable varieties of Navicula varians, a form to which I 

 have lately directed attention, as showing the extent to which 

 shape and outline may vary on the diatoms, without materially 

 affecting other characters. But my friend Dr. Greville has 

 suggested that the form in question is rather a Cocconeis, and 

 his opinion possesses much weight. 



III. Species now first described and figured. 



17. Cymbella?^ sinuata, W. G. — Dhu Loch in Glenshira, 



* I give a figure of Mastogloia OreviUei, first observed by Dr, Greville 

 in a gathering from the Pentland Hills. I subsequently found it in my 

 Lochleven gathering, but not having then seen Dr. Greville's species, I did 

 not at first recognise it. It is scarce on the gathering from Lochleven, 

 but will probably be found in abundance in some part of the lake, or in 

 some of the streams which supply it. 



t I am by no means sure that this form is correctly referred to the 

 genus Cymbella. I at one time supposed it might be a Eimotia, or a 

 Pinnularia, or possibly a Gomphonema. But the general opinion among 

 those to whom I have shown it is that it comes nearest to Cymbella. It 

 is marked, however, as doubtful. Some have conjectured it to be an 

 abnormal slate of some form, not specified. But it occurs in so many 

 localities, always with the same characters, that I cannot but regard it as 

 a normal and distinct sjiecies. Dr. Greville has recently met with it in 

 various gatherings from the vicinity of the Bridge of Allan, and I have 

 again found it in several from the neiehbourhood of Hamilton. 



