56 



idium, it has been affirmed, most decidedly, tliat in an early stage several spores 

 united together in a globose mass are included in a hyaline sac. Unless we greatly 

 misconstrue Rostafinski's observations, he denies that fact, that in any instance, 

 or at any stage, is there an investing membrane, and previous observers have, 

 therefore, been deceived in what they supposed they had seen. This is an issue 

 between Messrs. Berkeley and Broome and Kostafinski, and between them must 

 be decided. 



The other point to which I would allude is the structure of the capillitium 

 in the two allied genera Pkysarmn and Didymium. All who had any experience 

 of Myxogasters under the old system are aware, that often they were in great 

 difficulty in determining to which of these genera a specimen would belong. 

 According to the present arrangement there need be no such difficulty, since in 

 Physarum the capillitium forms a network, thickened at the angles ; and in Didy- 

 mium the capillitium consists of threads radiating from the columella to the wall 

 of the peridium. A pocket lens is often sufficient to detect this difference in 

 mature specimens of the two genera. 



There are other interesting features to which some allusion might have been 

 made, as for instance the ready and satisfactory manner in wliich Mr. Phillips 

 and myself determined a specimen of Cienkoiuskia, which he could not satisfac- 

 torily determine on the old method, and which consequently has been determined 

 as British since the publication of my revision of the British Myxogasters. An- 

 other satisfaction is one which I have experienced in examining a very large 

 number of specimens of Trichia, and found little or no difficulty in their deter- 

 mination within the limits fixed by Rostafinski. These are practical proofs of 

 the advantages which even a slight acquaintance with the method of classification 

 now proposed has over the old method. 



Having verified a great number of the figures reprinted in the "Revision" 

 by an examination of the species themselves, I can testify to their general accu- 

 racy, and in such instances as Clathroptycliium, the extraordinary structure which 

 Rostafinski has so well elucidated. 



It has always been said, that of all fungi the Myxogasters are the most 

 difficult for any but the most accomplished and experienced mycologist to deter- 

 mine, but such cannot now be affirmed with truth, since anyone with ordinary 

 intelligence and perseverance will have no difficulty with the genera, and but 

 little with the species. 



A FOSSIL FUNGUS. 

 Me. Woethington Smith, in his paper, said :— "I believe that the fungus 

 I have named Pcronosporitcs antiquarius, in the scarlariform axis of the stem of 

 a Lepidodendron from the Coal Measures, has, up to the present time, only 

 been examined in a somewhat slight manner, and has never been searchingly 

 looked into. No description, except that of a Mucor, also from the Coal Mea- 



