452 Systematic Paleontology 



Class ANGIOSPERMAE 



Subclass MONOCOTYLEDONAE 



Order NAIADALES 

 Family ALISMACEAE 



Genus ALISMAPHYLLUM gen nov. 



The present genus is proposed for monocotyledonous leaves of un- 

 known generic affinity but obviously referable to the family Alismacese. 

 The type species is Sagittaria Vidor-Masoni Ward based on a single 

 specimen from the Patapsco formation at Mt. Vernon, Virginia. It 

 was compared by its describer with the exisiting Sagittaria latifolia 

 Willd., but it would be equally at home in other genera, as for example 

 Ecliinodorus or LopJiotocarpus to mention but two such. The venation 

 is of the type of this family and the auricles suggest various species 

 of Sagittaria, although when aurieled the ears in the mature leaves are 

 usually much more extended than in the fossil leaf. Since, however, 

 there is considerable variation in this respect, some species having 

 lanceolate leaves and others like Sagittaria rigida Pursh having linear, 

 lanceolate, elliptical and hastate leaves, this character is not of impor- 

 tance. It is believed, however, to be of distinct advantage in cases 

 where certainty is impossible, not to carry the generic lines of the present 

 too far back into the past. The genus Alismacites of Saporta ^ is not 

 available since it was proposed for forms with a distinctly stated relation- 

 ship to the modern genus Alisma. 



A considerable number of fossil species from a large number of 

 horizons have been described as species of Alisma, Alismacites and 

 Sagittaria, tlie oldest being the leaves and seeds from the jSFeocomian 

 of Portugal which Saporta names Alismacites primcevus.^ 



The existing Alismacege number about 70 species segregated into 10 

 or 12 genera and all are aquatic or marsh plants of herbaceous stature 



^Saporta, Ann. Sci. Nat. Bot. (iv), tome xvii, 1862, p. 228. 



^Saporta, Fl. Foss. Portugal, 1894, p. 96, pi. xv, fig. 31; pi. xvi, fig. 13a. 



