144 Proceedings of the Royal Society of Edinburgh. [Sess. 
Vegetative hyphae showed no transverse septa. 
Reproduction. — 1 . Terminal, globular structures measuring 6/x to 14 p. 
are attached to liyphse, each by a short stalk. These are unicellular ; some 
are ruptured, the hole in the shell being circular and extending more than 
half way across the vesicle. These globules are in all probability the 
remains of swarm-sporangia, similar to those found in the modern Perono- 
sporaceae or Saprolegniaceae. 
2. Some of the thickest of the hyphae are divided by septa into a 
number of short cells, the hyphae as a result assuming a moniliform appear- 
ance. The short cells are held to be of the nature of oidium cells , sub- 
serving the purpose of rapid multiplication. 
A ffinities . — The fossil can be definitely assigned to the Phycomycetes, 
and among these the Saprolegniaceae are indicated as being the nearest 
allies among modern fungi. 
EXPLANATION OE TEXT-FIGURES. 
Text-figs. 1—4. Peronosporites gracilis. 
Text- fig. 1. Hyphae and attached vesicles in stem Lyginodendron Oldhamium. 
x 400. 
Text-fig. 2. Diagrammatic representation of disposition of vesicles depicted in 
Plate, fig. 3. 
Text-fig. 3. From cortex of stem of Lepidodendron aculeatum. Vesicle (c) is 
attached to hypha (b). Cell-walls of host shown at a. 
Text-fig. 4. From cortex of root of Lyginodendron Oldhamium. x 400. 
Text-figs. 5-8. Palaeomyces hacilloides. 
Text-fig. 5. From leaf -base of Lepidodendron, showing variation in thickness of 
branches. Compare a and b. x 250. 
Text-fig. 6. From leaf-base of Lepidodendron. Shows well-marked example of 
variation in thickness of branches, these varying from 1/x to 7 p. x 500. 
Text-fig. 7. Drawing of vesicle shown in Plate, fig. 8. x 2500. 
Text-fig. 8. From leaf-base Lepidodendron. At a, thick hypha is septated ; at b 
and c, hypha is much thinner than at a. Hyphse of varying thickness shown at d 
and e. x 800. 
EXPLANATION OF PLATE. 
Figs. 1-4. Peronosporites gracilis. 
Fig. 1. From cortex of stem of Lepidodendron aculeatum. x 250. 
Fig. 2. Same as fig. 1. Hypha seen traversing several cells. x 250. 
Fig. 3. From cortex of stem of Lyginodendron Oldhamium. Shows intercalary 
vesicles. 
