RECORDS OF MEETINGS 437 



there are exposures of lignitic shales and white limestone of the "younger 

 series"^ which rest unconformably upon the "older series'^ and which are 

 of Lower or Middle Tertiary age. In each locality vertebrate fossils have 

 been found associated with unquestioned marine invertebrates in both 

 the basal lignitic shales and the overlying Arecibo limestone. 



Professor Berkey has referred to these basal lignitic shales as a part 

 of the Arecibo formation.'^ It may be proved in the end that they should 

 be so classed, but for the present it will be well to separate the shales from 

 the limestone and use other names in referring to them. The name Col- 

 lazo is here applied to the lignitic shale beds in the vicinity of San 

 Sebastian, from the typical exposures on the Collazo Eiver, and the term 

 Juana Diaz to the shale beds in the vicinity of Juana Diaz^ particularly 

 the shale exposures on the Jacaguas Eiver to the northwest, west and 

 southwest of Juana Diaz. The term Arecibo is retained for the lime- 

 stone. 



The most important vertebrate find has been identified by Dr. W. D. 

 Matthew, Curator of Vertebrate Palasontology, American Museum of 

 Natural History, as a new species of ( ?) Halitherium (see page 439 be- 

 low). It consists of a lower jaw with three molar teeth and two vertebrae 

 of a primitive Sirenian. It was collected by Chester A. Eeeds, July 1, 

 1915, from the Juan Diaz shale exposures on the Jacaguas River one 

 kilometer north and one kilometer west of Juana Diaz. Other fossils, 

 some of them Sirenian, have been collected by Senor ISTarciso Rabell 

 Cabrero from the Collazo shales. They are in his private collection at 

 San Sebastian. 



The tooth of a fish belonging to the family Scombridse (mackerels and 

 their allies) was found in the Arecibo limestone exposures on the 

 Jacaguas River to the southwest of Juana Diaz, locality 199. 



A small, very delicate bone of an indeterminate teleost was collected 

 from the south bank of a ravine in the Juana Diaz shales, locality 226, 

 approximately 200 feet below the base of the Arecibo limestone, from the 

 exposure on the Jacaguas River to the southwest of Juana Diaz. 



A short distance below the road bridge over the Collazo River the tooth 

 of a hammerhead shark, Sphyrcena prisca Agassiz, was unearthed from 

 the lignitic shales exposed in the bed of the Collazo River. 



The tooth of Carcliarias magna (Cope) was collected from the base of 

 a 300-foot exposure of the Arecibo limestone in the east wall of the 

 Guajataca River canyon at a point where a native trail crosses the river. 

 It is on Sehor RabelFs ranch about ten kilometers northeast of San 

 Sebastian. 



«Ibid., pp. 11-17. 

 'Ibid., pp. 12-17. 



