136 MICHODICTYON 



possession bears the date 1870, the title page being dated 1871 ; 

 according to the reprint, therefore, we ought to regard Traut- 

 schold's species as having priority over Schenk's. Considering 

 the better material and much more complete diagnosis given by 

 Schenk, I propose to retain his name, in spite of the possible 

 priority of the Russian species. 



Schenk, in his first notice of Microdictyon Dunkeri, compares it 

 to Laccopteris elegans, Presl, of Rhsetic age ; in his second paper it 

 is transferred to Saporta's genus, and much new information is 

 added with regard to the fructification. He considers that the 

 fragments are most probably part of a palmately-divided leaf, 

 and agrees with Saporta that Microdictyon comes nearest to certain 

 species of the recent genus Polypodium. 1 



The smaller form from Portugal, named by Heer Laccopteris 

 pulchella* is admitted by the author of the species to bear a close 

 resemblance to L. Dunkeri, but it is separated on account of the 

 difference in size of the ultimate segments, and for some other 

 reasons, the force of which is not very clear. It is not improbable 

 that we might be right in including Heer's species in the list 

 of synonyms, but, considering the imperfections of the type speci- 

 men of L. pulchella, it is better, perhaps, to retain this additional 

 specific name. 



From the Cretaceous plant beds of Bohemia Velenovsky describes 

 some larger specimens than have been accessible to earlier writers; 

 they resemble in all points the smaller pieces figured by Schenk. 

 The affinity of the plant is discussed, and the two genera Gleichenia, 

 and Cyathea 3 are chosen as the most likely living ferns with which 

 the fossil form must be compared ; this comparison is founded on 

 the character of the sori, but Yelenovsky's specimens showed no 

 trace of the individual sporangia. He does not mention Schenk's 

 figures and descriptions of well-preserved fertile segments, although 

 the volume in which the Bohemian ferns are described bears the date 

 1888, twelve years later than the publication of Schenk's memoir. 



In Andrae's account 4 of the plants from the "Liassic" beds 

 of Steierdorf there are several figures of Andriania laruthina, 

 Fr. Braun, which are exactly similar in habit to Microdictyon 



1 Palaeontographica, vol. xxiii. p. 162. 



2 Secc. Trab. Geol. Portugal, 1881, p. 16, pi. xv. fig. 7. 



3 Abh. k. bbhm. Ges. Wiss. 1888, p. 13. 



* Abh. k.-k. geol. lieichs. vol. ii. Abth. iii. No. 4, p. 36, pi. vii. figs. 1-3. 



