GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 135 



articulating edge of the lower surface. Outer edge, proximal end, 

 and finger missing. Upper surface covered with coarse granulated 

 striae of very different lengths, varying from 1 to 10 or 12 granules, 

 and arranged obliquely longitudinally. Lower surface covered with 

 curved, wavy and punctate striae starting almost at right angles with 

 the inner margin, curving slightly forward and then abruptly back- 

 ward ; so that the greater part is more longitudinal than transverse ; 

 the striae are somewhat subdivided and followed outwardly by 

 shorter striae ; at the inner end they terminate abruptly, so that from 

 above the} 7 have the appearance of lo truncated shallow teeth. 

 Length 5.2 mm. 



This maims resembles that of two common recent species, P. 

 armatus (Gibbes) 1 , and P. galathinus (Bosc)\ both found on the At- 

 lantic as well as on the Pacific side of the continent. The upper 

 surface of the palm is similar in P. armatus, that is, it is ornamented 

 Avith short, irregular striae, which are, however, parallel to the inner 

 margin, while in the fossil form the}' diverge proximally from the 

 margin. The lower surface of P. avitus, on the other hand, resembles 

 more closely that of P. galathinus, but in the latter, the striae trend 

 more strongly forward on leaving the inner margin, and that margin 

 itself is not formed of such strongly marked teeth. 



Superfamily THALASSINIDEA. 

 Family AXIIDAE. 



AXIUS RETICULATUS, new species. - 

 Plate 57, figs. 2 and 3. 



Type-locality. — Panama Canal Zone. Las Cascadas section, Gail- 

 lard Cut. From lowest fossiliferous bed. Third bed below lowest 

 limestone beds separated by rows of nodules. Lower part of upper 

 half of Culebra formation. Oligocene series. D. F. MacDonald 

 and T. W. Vaughan, collectors. 1911. Station 6020a. 



Holotype. — Cat No. 324260, U.S.N.M. Left propodus of first 

 pereiopod, embedded in a nodule and showing the finger and the 

 greater part of the palm, except the proximal end and the distal 

 upper corner. An impression of the same is shown in another piece 

 of the nodule. The segment as uncovered is 14.3 mm. long, greatest 

 height 5 mm., length of finger 7 mm. The palm is greatly swollen 

 and at the top rounds over into a broad upper surface about 2.4 mm. 

 in width. The shell is considerably cracked and in life may not have 

 been as thick as it appears. The lower margin is sinuous, forming a 

 bay at about the distal third of the palm ; so far as the edge is pre- 

 served it is formed of small bead granules. The outer and upper 

 surface is ornamented with granules irregular in size and disposi- 



3 Porcellana armata Gibbes, Froc. Amer. Assoc. Adv. Sci., vol. 3, 1850, p. 190. 

 2 Porcellana galathina Bosc, Hist. Nat. Crust., vol. 1, 1802, p. 233, pi. 6, fig. 2. 



