iiS Bulletin 39 :290 



Shell more broad and solid than gahinensis of the Canal 

 Zone; whorls about 8, those of the spire with nearly straight or 

 only slightl}^ convex sides; last whorl large, broad, convex and 

 widest about the middle; the sculpture is much more coarseh^ re- 

 ticulate than in gatunensis, with the intersection points of the 

 ribs and spirals more or less subnodulose; the last whorl has 

 about 18 ribs, which on the back of the outer lip are more close- 

 ly spaced than elsewhere; the spiral cords are not so heavy as the 

 ribs, separated by wider interspaces which carry one or some- 

 times two very, fine, spiral threads; in addition, the spiral inter- 

 spaces are verj^ finely and neatly sculptured with fine, raised, 

 longitudinal lines, corresponding to the growth-lines; on the 

 spire- whorls there are 5 spiral cords, 13 on the last whorl and 3 

 more on the canal; canal short, twisted; aperture sub-ellip- 

 tical, with a moderately heavy, but not thickened outer lip and 

 internally lirated. 



Length 30, diameter 15.5, last whorl 21, spire 14.5 mm. 



A broader, more solid and more coarsely sculptured shell 

 than the Phos gatunensis of the Canal Zone, 



It was described from the Miocene of Paso Real, near Tux- 

 tepec, in the State of Oaxaca, Mexico, by Dr. Bose, whose excel- 

 lent figures agree exactly with specimens from Water Cay. The 

 several species of Phos, are often extremely abundant but local 

 in their distribution. Such is the case of Phos gaturiensis of 

 the Canal Zone, the Phos Moorei var. costaricenis of the Banana 

 River. Likewise in the present instance; the mexicanus, is a very 

 abundant fossil of the Gatun beds of the islands of the Chiriqui 

 Lagoon and the adjacent Valiente Peninsula. A few specimens 

 have also been collected in Costa Rica. 



Gatiin Stage: Water Cay. Toro Cay. Coco Plum, etc. 

 Rio Codes, C. R. 



Phos Moorei Guppy, var. costaricensis, n. var. Plate 9, figures 8, 9 



Shell of medium size, solid; spire long about one-half the to- 

 tal length of the shell; whorls 10, of which the first two belong 



