Maury — Porto Rican Tertiary Formation. 213 



although there is no actual superposition, as they occur 

 in different localities, twenty-nine kilometers apart. 



Dr. W. H. Dall in a letter dated June 12th, writes 

 regarding the Cerite molds, the Orthaulax and a few 

 other specimens that he was so good as to pass judgment 

 on "Most of your material recalls the Flint River upper 

 zone-, or Tampa silex bed horizon. ' ' 



(4) The fauna of the green shales on Rio Collazo near 

 San Sebastian is a very interesting and unique one. It 

 has at first glance what one might call a false Eocene 

 aspect. The fossils are all greatly distorted from pres- 

 sure. The most abundant and characteristic shell is a 

 Clementia like dariena from Gatun, but smaller and less 

 ventricose. It appears to be the Oligocene ancestor of 

 the Miocene C. dariena, and I am naming it G. rabelli. 

 With it was a new Area, most like A. balboai Sheldon 

 (=A. dalli Brown and Pilsbry, name preoccupied), 

 which Dr. Vaughan lists from the Culebra formation. A 

 representative set of Rio Collazo fossils was sent to Pro- 

 fessor Gilbert D. Harris, of Cornell University, well- 

 known as our leading American molluscan Eocene pale- 

 ontologist, with the request that he would kindly let us 

 know if they recalled any Eocene forms. Professor 

 Harris replied, in a letter dated May 27th: "I cannot say 

 that your fauna is related closely to any Eocene fauna 

 with which I am acquainted and my impression is that it 

 should go along with the later Tertiary. ' ' 



(5) On the south side of the Island near Ponce, Dr. 

 Reeds collected a large number of oysters all of one spe- 

 cies, and quite unlike the oyster which is very common in 

 the Collazo shales, and also entirely different from the 

 Guanica species. The Ponce oyster I identified as prob- 

 ably Ostrea cahobasensis Pilsbry and Brown, the type of 

 which was found near Las Cahobas and south of Tho- 

 monde, Haiti. Dr. Reeds sent a shell to Dr. Pilsbry who 

 very kindly compared it with his type and writes, "I am 

 disposed to identify it provisionally with the Haitian spe- 

 cies.' ' 



Mr. W. F. Jones 11 places the Las Cahobas and Tho- 

 monde beds somewhat below the Anguilla horizon. I 

 have placed these beds slightly higher in the following 

 correlation table, because of the fauna which Mr. Jones 

 lists from them 12 and because he does not mention finding 

 Orthaulax in the Haitian beds. 



u Jour. Geol., 26, p. 744, 1918. 

 12 Op. tit., p. 738. 



Am. Jour. Sci.— Fourth Series, Vol. XLVIIT, No. 285.— September, 1919. 

 15 



