140 cook: ivory palms in Panama 



learn the characters which enable the species to be distinguished. 

 In this respect the materials from Panama are of special value 

 for they show several new lines of specialization not previously 

 employed in the diagnosis of species. 



NEW CHARACTERS IN IVORY PALMS 



External sculpture of fruits. The species are all alike in having 

 the external shell of the fruit divided into raised polygonal areas, 

 each bearing a pyramidal tubercle or spine, but the areas are 

 larger in some species than in others and have larger or more 

 robust spines. In coarsely sculptured species the spines attain 

 a length of about 2 cm. ; in other species they are only half as long. 



Cortical fibers. These form a lining of close-set bristles on the 

 inner wall of the external shell of the fruit, to which they are 

 firmly attached. Indeed, the shell seems to be formed by a pro- 

 gressive hardening of the corky tissue in which the bases of the 

 fibers are embedded. The species differ notably in the develop- 

 ment of the cortical fibers, some having only short weak fibers and 

 others long stiff fibers. In most cases the fibers are about as 

 long as the external spines, but they may be longer or shorter. 



Pulj) fibers. The space between the cortical fibers and the true 

 mesocarp fibers that form a coating around the nuts is occupied 

 at first by a fleshy pulp. In some species the pulp seems to be 

 entirely fleshy, so that only an empty space is left'inside the cor- 

 tical lining after the pulp has disappeared. In other species there 

 is an open framework of loosely connected fibers, especially near 

 the base of the fruit. 



Mesocarp fibers. In addition to the pulp fibers there is a com- 

 plete fibrous sheath around each of the nuts, not unlike the meso- 

 carp of some of the cocoid palms, except that the fibers are not 

 attached to the shell of the nut. Some species of ivory palms 

 have the mesocarp fibers rather coarse and stiff, while in others 

 they are very fine and thin and are compacted into a fabric, 

 tough in some cases and brittle in others. Finally there are 

 cases where the mesocarp fibers are so slightly developed that no 

 coherent layer is formed and the dried pulp breaks away from the 

 surface of the nuts in angular scales. The mesocarp sheath may 



