LIST OF ILLUSTRATIONS 



Plates 



L — Relief Map of Porto Rico. 

 11. — Geological Reconnoissance Map of Porto Rico. 

 III. — Generalized Geological Cross-sections of the Island of Porto Rico. 

 I^'. — Right Pectoral Girdle and Limb of Sauripterus taylori Hall. 

 y. — -Illustrations of Biological Reductions of Selenium Compounds. 



Text Figures 



Page 



Relief features characteristic of the interior ranges of Porto Rico 8 



Partially destroyed dune sand deposits of the San Juan formation 11 



Unconformity below the Arecibo formation 16 



Typical shale occurrence 18 



Interbedded coamo limestone layers with massive tuffs 20 



Diorite porphyry sills 27 



Photomicrograph of a typical thoroughly indurated andesitic ash 30 



Photomicrograph of a typical weathered shale from Fajardo Play a 31 



Photomicrograph of a foraminiferal shale from the Bayamon-C<imerio 



road 32 



Photomicrograph of the San Juan formation indurated dune sand 33 



Shales and ash beds cut by a large irregular dike and sill 36 



Overturned fold and crush zone in finely bedded shales on the .Jayuya 



road near the summit of the range 38 



Crumpled shales as seen along the .Jayuya road near the summit of the 



range 40 



Cliff of the San Juan formation south of the lighthouse at Arecibo 44 



Detail of the double structure in the San Juan formation of Arecibo 46 



Playa plain and marginal terrace 48 



Structure beneath the marginal terraces 49 



Inner lowland near Bayamon 50 



Haystack (pepino) hills 51 



Cave structure in the haystack (pepino) hills 52 



View of a portion of Mona 73 



View of a portion of Desecheo 74 



Sandy plain south of Pinar del Rio, Cuba 125 



View near Banos San Vincente, Cuba 126 



Distribution of Archreidse 136 



Distribution of certain genera known from Baltic amber 137 



Distribution of Segestriinre 138 



One of the h^-pothetical upper Cretaceous land masses 139 



Curve of the consecutive means of temperature observed on the summit 



of Pike's Peak 156 



Thermopleionian variation of Port Darwin 158 



Temperatures recorded at some Asiatic stations 161 



iv 



