12 DR. GREGORY, ON SOME NEW SPECIES 



the Elchies gathering', where it is frequent, along with S. 

 biseriata and S. nohilix, so that it can be at once distinguished 

 from them. It has exactly the form of S. nobilis, but is 

 smaller and rather narrower in proportion. It differs from 

 S. biseriata in having one end round, the other acute. From 

 both of these species it differs still more in the fact of having 

 its canaliculi very much narrower and more numerous. Its 

 length is from -003 to "005 inch. Canaliculi fine, about 10 in 

 '001 inch. It is possible that it may be the perfectly deve- 

 loped S. linearis, but I have not as yet been able to ascertain 

 this. 



39. Gomphonema insigne, W. G., rude, Sm. — This species 

 was first observed in some gatherings from Duddingston Loch, 

 but I found it subsequently to be pretty widely distributed. It 

 is distinguished by its size and the coarseness of its striation. 

 The S. V. is doubly conical, the angle at the broadest part being 

 strongly marked. The F. V. is cuneate. Length from '002 

 to 0024 inch. Striae 18 to 20 in -001". I believe that 

 Mr. Smith has named this form, which I sent him when I 

 first observed it, G. rude, but I am not quite certain of this. 

 If so, there can be no objection to his name. 



40. Gomphonema ventricosum, W. G. — This well-marked 

 species occurs in a gathering from the banks of the Spey, 

 near Elchies, different from that which I have spoken of as 

 the Elchies gathering. The middle part is much expanded, 

 and both extremities are obtuse and rounded, the longer limb 

 being a little expanded at the apex. It is short and broad in 

 proportion, and very uniform in its characters. Length about 

 •0014 inch. Stria? about 30 or 32 in -001". Dr. Greville has 

 recently (April, 1855) found this species tolerably frequent in 

 several gatherings made by him near the Bridge of Allan. 



41. Gomphonema cequale, W. G. — This species occurs in 

 the Elchies gathering, which is from a spring in the grounds 

 of the house. I have seen it also in that from Elgin, and in 

 some of the other Banffshire gatherings, as well as in some 

 from Lanarkshire. It is shorter than tlie last, and is distin- 

 guished from it, as well as from other Gomphonemata, by the 

 position of the nodule, which is central, whereas in other 

 species it lies always nearer one end. In form it is linear 

 elliptical, but towards the extremities it is suddenly con- 

 tracted, and again expands, so as to be almost capitate. In 

 this it agrees nearly with some forms of G. tenellum, from 

 which, however, it differs, both in having much wider and 

 coarser striae, and in the central position of the nodule. 

 Length 'OOl inch. Striae rather distant, not reaching the 

 median line, conspicuous, about 22 or 24 in "OOl". 



