244 ANNALS OF SCOTTISH NATURAL HISTORY 



120. S. vestitum, Ralfs. Not common. Ross, Inverness, Aberdeen, 

 Kincardine, Perth. 



XANTHIDIUM, Ehr. 



1. X. aculeatum, Ehr. Not common. Sutherland, Aberdeen, 



Kincardine, Forfar, Perth, Dumbarton. 



2. X. antilopcenm (Breb.), Kg. Common. Of the two forms, the 



smaller, with slightly curved spines, is the more common. 

 This form has been found conjugated in Sutherland at Loch 

 Inver, and in Aberdeen at Logic Coldstone. The zygospore 

 is large, globular, with numerous stout, tapering, slightly bifid 

 spines, of which about 15 appear round the margin. Dia- 

 meter without spines, 60 //,; length of spine, i8/x. Our 

 Plate III. fig. 13, is from an immature specimen. Forma 

 supernumeraria, Nord., occurs in Sutherland near Loch 

 Inver. 



The other form is larger, with stout, almost straight spines. 

 A curious state of this form occurs in Loch Ruthven, 

 Inverness. It has a stout, short, blunt spine on the basal 

 angle, under the lower pair of spines, and with them forming 

 an equilateral triangle. 



Both forms are very constant in their characters, and each 

 probably forms a good species ; but not having seen the 

 zygospore of the larger form, it is thought better not to 

 separate them at present. 



3. X. ar mat u in, Breb. General. Has been found conjugated in 



Sutherland at Loch Inver, in Kincardine at Cammie, and in 

 Argyle in Glen Coe. 



4. X. Bigornanum, Perty. Very rare. Aberdeen Loch Ullachie 



near Ballater ; Kincardine Cammie. 



5. X. Brebissonii, Ralfs. Not common. Aberdeen, Kincardine, 



Forfar, Perth, Dumbarton. 



/3 basidentatum, Borg. Very rare. Aberdeen south 

 west from the Ord, near Dinnet ; Fife Tent's Moor. 



6. X. continuum, Archer. 



Var. Boldtiana, West. Very rare. Aberdeen Loch 

 Ullachie, near Ballater. 



7. X. cristatum, Breb. Not common. Sutherland, Ross, Inver- 



ness, Aberdeen, Kincardine, Forfar, Perth. 



ft uncinatum, Breb. Common. A curious form of this 



variety occurs in Loch Ruthven, Inverness, in which 



the central circlet of granules is replaced by a short, 



stout, blunt spine. 

 y Delpontii, n. var. (Delponte, "Spec. Subalp.," Tab. XIV. 



figs. 1-12). Extremely rare. Kincardine Scolty. 



