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Part III — Seventeenth Annual Report 



ation — viz., Forfar Loch and Duddingston Loch. An interesting point in 

 the distribution is that it does not appear to have yet been observed in 

 any of the lochs on the west side of Scotland, though it has been 

 observed in a few on the east side. 



Herpetocypris strigata, Miiller. — This, which is also a fine and large 

 species, appears to be somewhat restricted in its distribution. It was 

 during the present investigations observed only in Loch Leven and 

 Duddingston Loch. 



llyodromus olivaceus, B. and N. — The distribution of this species appears 

 to be also very restricted, though it may not be rare where it does occur. 

 Like Cypris pubera, it was obtained in Forfar Loch and in Duddingston 

 Loch. It may be of interest to refer to a somewhat curious feature in the 

 distribution of the two Ostracods Herpetocypris strigata and llyodromus 

 olivaceus as regards their occurrence at Duddingston Loch. On the 

 north-west shore of that loch — the part of the shore which is accessible to 

 the public — there are several large boulders, and at the foot of one of 

 them which is situated two or three yards back from the edge of the 

 water, the soil lias been excavated to a small depth along the front side, 

 either by the feet of people who are wont to use the boulder as a seat, or 

 by children digging about it. This hollow and the ground all round the 

 boulder is dry and hard for two or three months during summer ; but 

 from late autumn to spring the hollow is full of water which percolates 

 into it from the rising ground behind. Yet in this hollow, which in 

 summer is baked by the sun and trampled hard by the feet of people who 

 use the boulder as a resting-place, and where it is difficult to conceive how 

 anything could retain its vitality, I have found, year after year, in the 

 early winter and spring, a considerable abundance of Herpetocypris 

 strigata, together with a certain admixture of llyodromus olivaceus. 

 These are the only two species which I can remember having observed at 

 this place ; and it often puzzled me to find out how they were able to 

 survive the heat and drought of summer. Probably all the adults perish, 

 but the ova will be better able to resist the extreme conditions to which 

 they are exposed during the summer months. The two Ostracods referred 

 to, though more or less common here, are seldom obtained in the loch 

 itself. 



llyodromus robertsoni, B. and N. — A number of specimens of this com- 

 paratively rare species were obtained in Loch Doon. Its distribution, so far 

 as known, appears to be restricted to a few lochs in Scotland. Herpetocypris 

 strigata, llyodromus robertsoni, and llyodromus olivaceus show a certain 

 gradation of form which is somewhat difficult to describe clearly ; but 

 when actual specimens are compared, the one with the other, there is not 

 much trouble in discriminating the different species. 



Cyprois Jlava, Zadd. — Duddingston Loch appears still to be the only loch 

 in Britain in which this species certainly exists, and it is interesting to find 

 that the Cyprois is restricted to a comparatively small portion of the west 

 end of the loch. Moreover, the species is not found, except, perhaps, 

 rarely, in the loch itself, but in little pools in the marshy ground outside 

 the extensive mass of tall reeds that fringe the shore at this part. At 

 my last visit to Duddingston Loch I obtained specimens of the Cyprois 

 at the same part at which it was found a good many years ago. 



Candona acuminata, Fischer. — Specimens of this somewhat rare 

 Ostracod were obtained in Loch Lomond, along with Candona fahceformis 

 and one or two other species. 



