THE CARBONIFEROUS FLORA. 



171 



sisted of long slender cones or spikes, having whorls of scales bear- 

 ing the spore-cases. Some authors speak of Asterophyllites as only 

 branches and leaves of Calamites ; but though at first sight the re- 

 semblance is great, a close inspection shows that the leaves of As- 

 teropliyllites have a true midrib, which is wanting in Calamites, 



Genus Annularia. — It is perhaps questionable whether these 

 plants should be separated from Asterophyllites, The distinction is 

 that they produce branches in pairs, and that their whorls of leaves 

 are one-sided and usually broader than those of Asterophyllites, and 

 united into a ring at their insertion on the stem. One little species, 

 A, sphenophylloides, is very widely distributed. 



Pinnularia — a provisional genus-— includes slender roots or stems 

 branching in a pinnate manner, and somewhat irregularly. They 

 are very abundant in the coal shales, and were probably not inde- 

 pendent plants, but aquatic roots belonging to some of the plants 

 last mentioned. The probability of this is farther increased by their 

 resemblance in miniature to the roots of Calamites. They are always 

 flattened, but seem originally to have been round, with a slender 

 thread-like axis of scalariform vessels, enclosed in a soft, smooth, 

 cellular bark. 



Family Rhizocarpe^; Genus Sphenophyllum. 



Leaves in whorls, wedge-shaped, with forking veins. Fructi- 

 fication on spikes, with verticils of sporocarps. These plants are 

 by some regarded as allied to the Calamitem and Asterophyllitem, by 

 others as a high grade of Rhizocarps of the type of Marsilia. The 

 stem had a star-shaped central bundle of scalariform or reticulato- 

 scalariform vessels. 



Genus Sporangites. (Sporocarpon, Williamson.) 



Under this name we may provisionally include those rounded 

 spherical bodies found in the coal and its accompanying beds, and 

 also in the Erian, which may be regarded as Macrospores or Sporo- 

 carps of Protosalvinia, or other Rhizocarpean plants akin to those de- 

 scribed above in Chapter III, which see for description. 



Genus Protosalvinia. — Under this we include sporocarps allied 

 to those of Salvinia, as described in Chapter III. 



Family Filices. 



Under this head I shall merely refer to a few groups of special 

 interest, and to the provisional arrangement adopted for the fronds 

 of ferns when destitute of fructification. 



