Notes on a Fast- Tertiary Fresh- Water Be'posit. 335 



This marl, which is very pure, is similar to that observed 

 at Blackford Hill, referred to in " Ancient Lakes." In it are 

 numerous small irregular concretions of a bluish colour, which 

 were found to consist of carbonate of lime, mixed with a 

 little earthy matter and iron, the latter being possibly the 

 colouring agent. As far as has been ascertained, the extent 

 of the deposit is somewhat limited. In the portion examined, 

 organic remains, chiefly Molluscan and Entomostracan, were 

 found to be more or less abundant. It is very probable that 

 the fine chalk-like matrix in which the remains are imbedded 

 consists mainly of comminuted shell debris, and to this 

 source is probably also due the mineral concretions referred 

 to. Though Molluscan remains were common, they comprised 

 very few species — Fisidiiim pusillwn, Limncea peregra, 

 L. truncatula, and Flanorhis nautileus being nearly all the 

 truly aquatic forms observed. A few others, such as Succinea 

 jnotris, Helix _/:)?^^cAe//a, Vertigo pygmcea, var.,^ were also 

 noticed, and these were probably blown into the loch or 

 washed down by rain from somewhere in the vicinity. A few 

 seeds of flowering plants, spores of Ghara, and macrospores of 

 Isoetes also occurred in the material examined, the last being 

 frequent. The Crustacea, however, are the most interesting 

 of the organic remains found in this deposit. Three species 

 of these are, so far as I know, now recorded for the first time 

 as fossil, viz., Frpetocypris strigata (0. F. Miiller), Frpeto- 

 eypris tumefacta (Brady and Eobertson), and Cyprois flava 

 (Zaddach). It may be stated in passing that all three are 

 foimd living in Duddingston Loch. Some time ago I 

 exhibited to this Society a few type-slides of species of 



^ This shell, which was of frequent occurrence iu the marl, is rather 

 smoother and more glossy than the typical Vertigo 'pygmcea. It diifers chiefly, 

 however, in the mouth heing unfurnished with teeth. The absence of these 

 cannot be ascribed to erosion, for even iu those shells that are in perfect 

 l)reservation no trace of teeth can be observed. In this respect it agrees with 

 V. cdentula, but the form of the shell is certainly that of V. pygmcca. From 

 its neat appearance I propose, provisionally, to name this variety F. pygmma, 

 var. concinna. [Since the foregoing note was written I have had a communi- 

 cation from Mr J. W. Taylor, F.L.S., Leeds, in which he states that, in his 

 opinion, this Vertigo belongs to a new species. In that case the name con- 

 cinna will become specific instead of varietal.] 



