218 Bibliographical Notices. 



plant Mr. Brown suspects it to be minutely cellular, in which state 

 he has observed it to occur in the nascent sori of several species of 

 Polypodium, the peculiarity in the present instance consisting merely 

 in its prolonged duration. 



The second article relates to another species of Polypodium (P. 

 papillosum, Bl.), which is described by Mr. Bennett as forming part 

 of the same section with P. vulgare, and is chiefly remarkable as the 

 only described species with immersed sori, belonging to that subdi- 

 vision, and for the extent to which the immersion is parried, the sori 

 "being completely buried within the sac, which forms a mammillary 

 protuberance of considerable height on the uj)per surface of the frond." 

 Mr. Bennett makes some observations on the differences in venation 

 which occur in this great section ; and particularly notices two un- 

 described species belonging to it as interesting on account of re- 

 markable peculiarities connected with their sori. 



The third article has for its subject a grass, formerly referred to by 

 Mr. Brown, in his * Chloris Melvilliana,' appended to th6 narra- 

 tive of Captain Parry's First Expedition, under the name of Ataxia, 

 and since introduced by M. Kunth, from the characters there given, 

 into his ' Enumeratio,' with the specific name of Horsfieldii. It is 

 described by Mr. Brown as in habit and structure exactly interme- 

 diate between Anthoxanthum and Hierochloe, in conjunction with 

 which it forms " a very natural and well- characterized section, which 

 belongs rather to the tribe Avenacece than to Phalaridece." " In all 

 of them," he observes, " the upper valve of the hermaphrodite flos- 

 culus has a single nerve occupying its axis, and one of the two sta- 

 mina is placed opposite to this nerve. The co-existence of these two 

 characters, both of which are remarkable deviations from the usual 

 arrangement in Graminece, seems to invalidate the hypothesis re- 

 specting the composition of the inner valve of the flower of this 

 family. It might, however, be assumed that the median nerve in 

 these genera is formed of two confluent cords, a view to a certain 

 extent supported by the somewhat analogous structure in the corolla 

 of Composite. It might also be assumed that the stamen belongs to 

 the inner or complementary series, which is rarely developed in tri- 

 androus grasses." In connexion with this subject Mr. Brown also 

 notices two remarkable genera found in Abyssinia, the one by Dr. 

 Riippell, and the other by Professor Ehrenberg ; and particularly 

 describes the very singular modification of structure which is found 

 in the former. 



With reference to the difference in the number of stamina between 

 the male and hermaphrodite flowers of Ataxia and Hierochloe, Mr. 



