T. D. A. Cockevell — Descriptions of Tertiary Plants. 65 



Art. Y. — Descriptions of Tertiary Plants ; by T. D. A. 



CoCKERELL. 



1. A Frog^s-bit from Florissant, Colorado. 



Limnobmm obliteration sp. nov. Figure la. 



Blade of leaf nearly circular, with a reniform base ; 

 obscurely about 10-nerved, these nerves simple, and exactly as 

 in the living L. spongicc. Length from insertion of petiole to 

 apex about 31 mm , from apex of basal lobes to apex 35 ; breadth 

 36. Margin perfectly entire, somewhat thickened. The apex 

 is broadly rounded, with no tendency to pointing, such as is 

 seen in the living L. sjpongia. 



This is the first fossil species of this group from America ; 

 but a similar plant occurs in the Miocene of Europe, and has 

 been named by Heer Hydrocharis orbiculata ; " distinguished 

 by its circular leaves, which no doubt floated on the surface of 

 the water like the leaves of water-lilies." 



Hah. — Florissant, in the Miocene shales, Station 14 ( W. P. 

 Cockerell, 1907). Peabody Museum, Yale, Cat. No. 1001. 



2. Two Maples from Florissant. 



Acer perditum sp. nov. Figure lb. 



Leaf with the blade deeply trilobed, the sinuses extending 

 about half way to the base ; the lobes broad, pointed, the mid- 

 dle one broadest about 9 mm from its base, thence slightly con- 

 tracted basally ; prominent nervures three, but also a smaller 

 one on each side; margin obscurely and rather remotely den- 

 tate. As preserved, the blade is yellowish, while the petiole 

 and principal nerves are dark brown. Length of blade, about 

 44 mm , breadth about 31 ; breadth of middle lobe in middle, 

 12 mm , at base, 10 mm ; length of middle lobe about 21-i mm ; of 

 lateral lobes 20 or less. There is some resemblance to such 

 fossil species as Aralia notata Ward, but the venation is very 

 different, and agrees with that of Acer. Acer narbonnense 

 Saporta, from the Oligocene, is a, somewhat similar leaf, differ- 

 ing however in its margin, and in the much less broadened 

 base. The Chinese A. wilsoni Render is similar in general 

 form, but its lobes are far more attenuate, its margins are almost 

 completely entire, and the extra basal (external) veins are 

 absent. There is also resemblance to A. saccharum rugelii 

 (Wesm.) Rend., which, according to Sargent, is a leaf-form 

 sometimes appearing on the upper branches of trees wdiich 

 have on their lower branches the leaves of typical A. saccha- 

 rum. In the southern states, however, the rugelii form is 



Am. Jour. Sci. — Fourth Series. Vol. XXVI, No. 151. — July, 1908. 

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