330 Rev. W. A. Lcighton on new British Arthonise. 



to this point. In Bursaria Vorticella we may detect the following 

 fact : as soon as the contractile vesicle which lies at the pos- 

 terior end of the body has contracted, we may observe at the 

 margins of the animalcule, in its usual position of swimming, 

 that two long narrow cavities originate, tilled with transparent 

 colourless fluid, and these stretch from opposite the mouth 

 as far as the region of the contractile vesicle. They both gra- 

 dually enlarge, and thus approach near to the anal point ; here 

 they meet, lose their often very irregular form, and change into 

 the globular : the remaining contents of the body are displaced 

 upwards by this ; and then these globular reservoirs contract 

 until they vanish, without it being perceptible where the fluid 

 has been driven to ; after some time the narrow light streaks 

 reappear, and the process is repeated in the way above-described. 

 The aflerent canals, therefore, are not filled at the commencement 

 of the systole. But must this not be so much the more expected, 

 if the fluid flowed back in the same path as it came in, the 

 vanishing of the contractile vesicle taking place much more 

 rapidly than its production ? 



I have never yet found in any Infusorium special canals in 

 which the fluid is seen to flow back into the body during the 

 systole, and which would give the means of a perfect circulation. 



The facts stated in this paper were first made pubhe at the 

 meeting of the Berlin " Naturforscheude Freunde," June 19, 

 ]855. 



XXIX. — New British Arthonire. 

 By the Rev. ^\ . A. Leighton, B.A., F.B.S.E. 



[With a Plate.] 



Since the publication of my Monograph of British Graphidea, 

 the following species of Arthonia, new to our flora, have occurred 

 to my notice. 



1. Arthonia glaucomaria, Nyl. Thallus none j ardellse hy- 

 menicolar, sessile, round; disk black, flattened, more or less 

 convex, dull ; sporidia in asci, eight, oblong, 1- 2- 3-septate. 



Arthonia glaucomaria, Nyl. Nouv. Class. Lich. (2 Mem.) in Mem. Soc. Sc. 

 Nat. Cherbourg, 3. 189 (lS55j; Syn. Arthoniarum in Me'm. Soc. Sc. 

 Nat. Cherbourg, 4. 98; Leight. Lieh. Brit. Exsic. 24?! 



Parasitic on the apothecia of Lecanora glaucoma, Ach. 

 Haughmond Hill ! Caer Caradoc ! and Long Mynd ! Shrop- 

 shire. Barmouth ! N. Wales. Cliff'rigg, Cleveland, Yorkshire ! 

 Thallus undistinguishable from that of the matrix. Ardelhn 



