GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 29 



spreads naturally along the inner beaches, while attempts to intro- 

 duce others of the most highly esteemed American species in the 

 Orient have failed. From its prevalence among the existing species 

 the habit of growing in wet, shaded soils is evidently an old one, and 

 since the Wilcox Anonas are associated with a strand flora the as- 

 sumption that they grew on the inner beaches or the shaded and 

 more swampy edges of lagoons possesses every degree of probability. 



In the pipe clays of Alum Bay which were contemporaneous with 

 the Wilcox there are two species of Anona, and Engelhardt has de- 

 scribed two species from the Eocene or Oligocene of Chili. The 

 Oligocene record shows a species in France and a second in Saxony. 

 In the Miocene there are two species each in England, Styria, and 

 Croatia, and one each in Bohemia, Colorado, and Transylvania. 

 There is one each in the Pliocene of France and Italy, showing how 

 modern was their extinction in the south of Europe. 



The genus Asimina has only four or five recorded fossil species. 

 These are all American except for a form from the Pliocene of Italy 

 which has been referred to this genus, although I suspect that it 

 represents Anona, since Asimina appears to have originated and been 

 confined to the Western Hemisphere. The oldest known species is 

 based on foliage which is found in the basal Eocene of the Rocky 

 Mountains (Denver formation) and of the embayment (Midway 

 Group). There is a single species based on a seed from the basal 

 Wilcox and no other records except a form close to the modern 

 from the late Miocene of New Jersey (Bridgeton sandstone) and the 

 occurrence of the existing Asimina triloba Dimal in the interglacial 

 beds of the Don valley in Ontario. There are 17 existing species of 

 Anona recorded from Central America, six of which are known from 

 Panama. Hemsley records 11 species of Guatteria from Central 

 America, at least two of which occur in Panama. 



Occurrence. — Culebra formation, upper part. East wall of Gail- 

 lard Cut just north of Canal Commission station 1760 (collected by 

 M. I. Goldman). Gatun formation. Gatun borrow pits (collected 

 by M. I. Goldman). 7 miles northeast of Bejuca near Chame 

 (=Caimito formation) (collected by MacDonald). 



Family MYRISTICACEAE. 



Genus MYRISTICOPHYLLUM Geyler. 



MYRISTSCOPHYLLUM PANAMENSE, new species. 



Plate 13, fig. 3. 



Description. — Leaves ovate or ovate lanceolate in outline with 

 pointed apex and base, entire, evenly rounded margins, subcoriaceous 

 in texture. Length about 9 cm. Maximum width, midway between 

 the apex and the base, about 3.3 cm. Petiole slender, about 8 mm. 

 long. Midrib slender. Secondaries thin, about 8 subopposite ascend- 



