350 J. G. WALLER ON PARASITIC VEGETABLE ORGANISMS. 



group, which excavates chambers in common. Figs. 20, show 

 examples illustrative of the above remarks, and, in one instance, 

 some spores are seen within the conceptacle. At Figs. 21, 22, 23, 

 we have the confluent development, the first showing the plant 

 complete, the two others the cleared or exhausted excavations, the 

 circles mark the openings of the burrows. The confluent character 

 I shall again refer to, but at present must pass to the consideration 

 of a very rare species from a particle in the Galloper Sand, having 

 no connection whatever with any of those previously described, 

 except its globose form, and a diameter of 1000th of an inch 

 (Plate XV., Fig. 1). It shows its surface to be formed of a net- 

 work of ovate spores. At Fig. 2, is a thallus upon which two 

 younger forms are developing. I refrain from either classifying 

 this example or pointing out analogies, that belongs to those more 

 acquainted with this department of natural history. Not more than 

 five figures have been found, and only one, that given at Fig. 1, is 

 complete. 



We now pass to a species altogether distinct in character, which is 

 interesting because of its similarity, in many ways, to what Prof. 

 Duncan found in Silurian Corals. It is always in flat, not rounded, 

 surfaces, burrowing in tubes of a generally equal diameter, begin- 

 ning at the edges of the particles and meandering through them 

 with occasional apertures to the surface, probably for discharging its 

 spores, not interfering or anastomosing with each other, and avoid- 

 ing any other excavation in its progress. It is not so frequent to 

 find this in a complete state, but more often its exhausted tubes, 

 yet, when found, it is of the same cinnamon brown colour, which is 

 most prevalent amongst these organisms. 



PI. XIV., Fig. 1, is an example of that described, not containing 

 any of its plasmic matter, and showing the circular apertures on the 

 surface. The mean diameter of the tubes is about the 777th of an 

 inch. There are other forms possessing the same characteristics, 

 though, perhaps, with more simplicity, whose diameter is about the 

 2000th of an inch, but it is impossible to say how far they are to be 

 regarded as separate. But at Fig. 5 is a form so distinct as to re- 

 quire a special notice, and as this was found intermingled with the 

 last, it must be separated as another species. It has the singular 

 habit of tubes quadradiate from a square centre, which extend at 

 considerable length, and which have an extremely regular diameter 

 of the 2000th of an inch. When, however, we pursue these lengthened 



