GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 151 



CALLIANASSA STRIDENS, new species. 



Plate 61, figs. 12-14. 



Type-locality. — Panama Canal Zone. From third hard sandstone 

 bed from bottom. Las Cascadas section. Upper part of Culebra for- 

 mation. Oligocene series. D. F. MacDonald and T. W. Vaughan.. 

 collectors. 1911. Station 6019e. Cat. No. 324281, U.S.N.M. 



Holotype. — Manus of a left cheliped. Only the upper two-thirds 

 is visible, the lower third is embedded in rock. Upper margin 

 horizontal, distal and proximal margins vertical, supero-posterior 

 corner rounded. Upper edge thin, a little sinuous, viewed from the 

 top. On the inner surface a little below the upper edge there is a 

 row of 8 short vertical ridges, which occupies the whole length of 

 the segment. This may have been a stridulating mechanism. 



Measurements. — Superior length of manus, 11 mm.; thickness, 

 3.1 mm. 



CALLIANASSA MAGNA, new species. 



Plate 62, figs. 1-3. 



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. Cat. No. 

 324270, U.S.N.M. 



Measurements. — Greatest length of movable finger (tip broken 

 off) , 33 mm. ; greatest height, 13.2 mm. ; thickness, 0.8 mm. ; length 

 of basal sinus, 6 mm. 



Holotype. — The only specimen is a movable finger or dactjdus of 

 the right cheliped. It is very much worn and a considerable portion 

 of the tip is lacking. The lower border is thin, but the remainder 

 is thick and in cross section subcircular, and tapers gradually to- 

 ward the distal end. At the proximal end below there is a broad 

 sinus ; the thin prehensile edge is slightly concave, viewed from out- 

 side, and feebly denticulate, especially when viewed from inside; 

 there is a somewhat larger and better preserved tooth just within the 

 margin at the widest part of the finger. Upper margin in outer view 

 straight in its proximal half, gently curved distally. In dorsal 

 view the finger is much curved and in the middle of its upper surface 

 there is a longitudinal row of four large punctse. 



In its general shape, including the basal sinus, this dactylus re- 

 sembles that of C. pellucida Rathbun, from the Leeward Islands, 

 a description of which is about to be published by the Carnegie In- 

 stitution, but the prehensile edge is thinner and more laminate and 

 the inner outline more concave in dorsal view instead of almost 

 straight as in that species. 



