Floristik u. Systematik der Phanerogamen. — Palaeontologie. 445 



Small (V. cinerea Floridana Munson). V. Linsecomii lactea Small (V^ 

 Llnsecomii glaiica Munson). V. rufoinentosa Small. 



Willugbaeya heterophylla Small. W. Halei Small. 



Xanthisma Berlandieri Small (X. Texaniim Berlandieri A. Gray). 

 Xanthoxalis coniiciilata Small (Oxalis cornicidata L.). X. Langloisii 

 Small. X. filipes Small (O. filipes Small). X. macrantha Small (0. 

 coniiciilata macrantha Trelease). X. Texana Small. X. stricta Small 

 (0. stricta L.). X. Bnsliii Small (0. Biishii Small). X. riifa Smali (O. 

 riifa Small). X. colorea Small. X. recurva Smail (0. reciirva EH.). X. 

 Brittoniae Small (0. Brittonlae Small. X. interior Small. X. grandis 

 Small (0. grandis Small.). X. cymosa Small (O. cymosa Small). X. 

 hirsiiticaulis Small (0. hirsiiticaulis Small). X. Priccae Small (0. Priceae 

 Small. Xolisma foliosiflora Smali {Ändromeda parJciilata foliosiflora 

 Michx.). Xylophacos Missoariensis Rydb. (Astragaliis Missoiirtensis Nutt ). 

 Xyris arenicola Small {X. torta Kunth). X. pallescens Small {X. torta 

 pallescens C. Mohr). 



Yeatesia viridiflora Small {Rhytiglossa viridiflora Nees). 



Zy gophyllidium hexagoniim Small {Euphorbia hexagona Nutt.). 



Trelease. 



Arber, E. A. N., On Homoeomorphy among Fossil 

 Plants. (Geological Magazine. Dec. IV. 1903. Vol. X. 

 p. 385—388.) 



It is pointed out that certain fossil plants, which are usually 

 regarded as belonging to distinct genera, nevertheless possess 

 a striking series of characters in common, such as, for instance^ 

 similarities of habit. Examples may be found in plant bearing 

 rocks of many difierent ages. In the Goal Measures, the habit 

 of Alethopteris is strikingly similar to that of Lonchopteris, the 

 latter being distinguished chiefly by the reticulate nervation. In 

 Neiiropteris and Linopterls, a curious paralleüsm of habit extends 

 to species vvithin the genera; for instance, Neiiropteris gigantea 

 corresponds closely with Linopterls Brongniarti although 

 clearly distinguished by the non- reticulate nervation in the 

 former species. Other instances may be found in Otozamites 

 and Dictyozamites of Lower Oolite age, and possibly in Rhip- 

 tozamites and Noeggerathiopsis from the Permo-Carboniferous 

 rocks. 



Light has recently been thrown on the problem of the 

 meaning of these similarities in the case of certain invertebrate 

 remains, especially the Jurassic Brachiopods, and the Graptolites,, 

 which present phenomena closely similar to those observed 

 among fossil plants. Mr. S. S. Buckman, in particular. has 

 shown, with regard to the Brachiopoda, that species descended 

 from different Stocks may attain to a number of characters in 

 common by paralielism of development, which, as it 

 were^ overshadow their distinctive and ancestral characters. It 

 has also been possible to trace out the steps whereby two 

 lines of descent have converged towards the production of 

 homoeomorphs or species possessing a marked aggregate of 

 characters in common. 



It is suggested that similar instances of homoeomorphy among 

 the fossil plants may be explained by regarding them as „the 



