GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 179 



lateral and. nearly as broad as long; the proximal end is broken off, 

 the distal end is embedded in a hard matrix. The two upper sur- 

 faces are each not much more than half as wide as either of the two 

 lower surfaces. The upper, inner and outer margins are armed with 

 irregular spines and tubercles, the loAver margin with tubercles only, 

 which are not in a single row ; the surfaces also have a few scattered 

 spines and tubercles. The tips of most of the spines are broken off; 

 the largest spines are one on the upper margin near the proximal end 

 (of the specimen), and one just above the outer margin in the middle 

 third. The distal extremity of the segment widens in a manner sug- 

 gestive of the propodus of a Parthenopid, but it is not triangular- 

 prismatic as customary in the propodal segments. 



PARTHENOPE PLE1STOCENICA, new species. 



Plate 61, figs. 10 and 11. 



Type-locality. — Panama Canal Zone. From near Mount Hope in 

 ditch through swampy ground. About one-quarter mile from pres- 

 ent sea beach, 6 to 8 feet above high tide. Pleistocene series. D. F. 

 MacDonald, collector. April, 1911. Station 5850. Cat, No. 324247, 

 U.S.N.M. 



Holotype. — Propodal finger of right and major chela; lower proxi- 

 mal portion missing. Lower margin, so far as it remains, nearly 

 straight, tip upturned; upper margin broad at the proximal end 

 and armed with 5 unequal blunt teeth; the first or that nearest the 

 palm is broadly united with the second which is much larger ; third 

 of similar size and shape to the second and well separated from it; 

 fourth much smaller and fifth minute. Four lateral rows of punctae, 

 one either side of the prehensile teeth, and one through the middle 

 of the inner and of the outer surface, The posterior half of both 

 surfaces is sparsely covered with prominent and very unequal 

 granules. 



Parthenope excavata (Stimpson) 1 of which there is an example 

 from Panama in the United States National Museum collection has 

 a similar prehensile surface, but the lateral face is shorter and higher 

 and is granulate all over outside. 



EXPLANATION OF PLATES. 



Plate 54. 



Gatunia proavita Rathbun, holotype, dorsal view, X f. 



Plate 55. 



Gatunia proavita, holotype, ventral view, X i. 



1 Lambrus excavatus Stimpson, Ann. Lye Nat. Hist. New York, vol. 10, 1871, p. 98. 



