GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 161 



the segment differs from both those genera in lacking the crest on the 

 lower margin of the palm. 



Family LEUCOSIIDAE. 



LEUCOSILIA JURINEI (Saussnre). 



Gruaia (ilia) jurinei SAUSSUBE, Rev. et Mag. de Zool., No. 8, 1853, p. 12, 



pi. 13, fig. 4. 

 Leucosilia jurinii BELL, Trans. Linn. Soc. London, vol. 21, 1855, p. 295, pi. 32, 



fig. 1. 



Locality. Panama Canal Zone. From near Mount Hope in ditch 

 through swampy ground. About one-quarter mile from present sea 

 beach, 6 to 8 feet above high tide. Pleistocene series. D. F. Mac- 

 Donald, collector. April, 1911. Station 5850. 



Material. Six small arm- joints more or less worn; four of them 

 are incomplete at one or both ends. 



Size. Length of a large one, 5.6 mm. 



Distribution of Recent Material. Ranges from Mazatlan, Mexico, 

 to Peru and the Galapagos Islands. 



LEUCOSILIA BANANENSIS, new species. 



Plate 57, figs. 6-8. 



Type-locality. Banana River, Costa Rica. Probably equivalent 

 to Gatun formation. Miocene series. D. F. MacDonald, collec- 

 tor. 1911. Station 5882A, 56, 1 arm. holotype, from seventh fos- 

 silif erous zone below the uppermost one of the section. Station 5882^, 

 5#, 1 arm, paratype (a) , from sixth fossiliferous zone below the up- 

 permost one of the section. Station 5882/, 3/, 1 arm, paratype (6), 

 from fifth fossiliferous zone below the uppermost one of the section. 



Types. Cat. Nos. 324230, 324231, and 324232, U.S.N.M. 



Measurements. Length of holotype, 11.1 mm.; greatest diameter, 

 4.2 mm. 



Represented by only 3 arms from 3 different layers. The best 

 specimen represents the left arm nearly complete, lacking only the 

 distal articulating edge. 



Shape subcylindrical, slightly compressed in a vertical direction, 

 the greatest diameter being proximal to the middle, the smallest 

 diameter at the proximal end. The ornamentation consists of 

 tubercles or large granules, the granules becoming small at both ends 

 of the arm ; around the middle of the segment the granules number 

 about 15 ; the tops of the granules are broken off so that they appear 

 much flatter than they really were. Compared with L. jurinei, the 

 arm is more swollen, the granules less numerous, more equal and 

 further apart. 



