228 Professor Williamson on some [Feb. 16, 



Another group of anomalous objects bas been found in tbe coal- 

 measures, to wbich I have given tbe provisional name of Sporocarpon. 

 These are small, spherical, hollow, cellular structures, often filled 

 with free-cells, reminding us of many of the reproductive structures 

 of the Ehizocarpous plants. I have little doubt that these are truly 

 reproductive structures, but we have as yet wholly failed to discover 

 to what known fossil plants they belong, or to what order they must 

 be assigned. Yet, as in the case of some other objects to which I have 

 already referred, they are so far from being rare, and their individuality 

 of form is so marked, that they cannot have been unimportant morpho- 

 logical members of the Palfeozoic Vegetable Kingdom. They represent 

 links in the scale of life — but we know not what. 



The multiplicity of these indeterminable structures is great, and 

 consequently apt to discourage the investigator ; at the same time he 

 has his encouragements, since some that have long been equally 

 obscure have at length rewarded persevering research by yielding up 

 their secrets. Two instances may be quoted as examples of forms 

 with which we have long been familiar, but whose true nature has 

 been ascertained but recently. In the first of these our success has 

 been but partial. I long ago discovered numerous small spherical 

 objects, especially in the lower Carboniferous beds at Halifax, to which 

 I assigned the name of Zygosporites (Fig. 8) : similar objects appear 



to have been met with in France, and were 

 Fig. 8. believed by one French naturalist to be Zygo- 



spores of the well-known aquatic living group 

 of the Desmidese. I saw no sufficient reason 

 for recognising the existence of Desmids during 

 the Carboniferous age. The problem has been 

 solved by the recent discovery of these objects 

 in the interior of a true Sporangium, proving 

 them to be the spores of some Cryptogamic 

 plant very diiferent from a Desmid. Thus much 

 is finally settled. But we may venture further 

 and say that they are the spores of a Strobilus, which I some time 

 ago described under the name of Volhnannia Dawsoni. We have yet 

 to learn with certainty to what plant this Strobilus has belonged. 

 The probabilities are that it was Asterophyllitean. 



My second instance is still more important in its bearing upon 

 Palaeontological Darwinism. Some years ago a very remarkable 

 specimen was discovered in the lower coal-measures at Granton, near 

 Edinburgh, to which the name of Pothosites Grantoni was given, and 

 which has been quoted by Sir Charles Lyell and others * as a flower- 

 ing plant. Lyell says, " The fossil has been referred to the Aroidiae, 

 and there is every probability that it is a true member of this order. 

 There can at least be no doubt as to the high grade of its organisation, 



* 'Students' Elements of Geology,' p. 424. Balfour's 'Palaeontological 

 Botany,' p. 66. 



