138 PROCEEDINGS OF THE PALEOXTOLOGICAL SOCIETY 



CAMBRIAX AXD OBDOTICIAX FAUXAS OF SOUTHEASTERX XEWFOUXDLAXD 



BY GILBEBT VAX IXGEX 



i Abstract) 



Cambrian and Ordoviciau rocks aggregating some 10.000 feet in thickness 

 are well developed in the synclinal troughs of Conception and Trinity bays, 

 where they exist as remnants of original wide sheets infolded in the faulted 

 and overthiaist synclines of a fiord coast. The Cambrian stages characterized 

 by Holmia, Protolenus. Paradoxides. and Olenns are succeeded by Lower 

 Ordovician shales carrying the fauna of the Welsh Tremadoe, as indicated by 

 the presence of Dictyograptus, Shumardia, Parabolina, and Angelina. These 

 are overlaid by a series of water shoal, ferruginous sandstones, and sandj' 

 shales carrying a fauna of inarticulate brachiopods like those of the Armoricain 

 Grit of Normandy. A sudden change from arenaceous sediments with iron 

 oxides to a shaly facies with iron sulphides marks the introduction of abundant 

 graptolites of the Didymof/raptus nilidus type, together with thin-shelled 

 Orthoceratites, indicating a depression of the region during Arenig time to 

 permit the passage of oceanic currents. A return to shoal water bay deposits 

 is seen in the higher arenaceous ferruginous zone, which carries Asaphid and 

 Calymennid trilobites and Schizocranian brachiopods. The highest beds of 

 the district are spherulitic hematites, similar to those below, and fine-grain 

 black shales carrying Schizocrania, Lingula leseueri. and Westonia,- possibly 

 of Llandeilo age. All the Cambrian and Ordovician faunas observed in the 

 Avalon Peninsula appear to be related to the Welsh-French facies rather than 

 to the interior North Americau-Northen Scottish facies. 



"LARAMIE f" PUERCO AXD TORREJOX IX TEE SAX JUAX BASIX, XEW MEXICO 



BY WILLIAM J. SINCLAIR 



(Abstract) 



Near Oio Alamo, New Mexico, a continuous section through the so-called 

 "Laramie" and the overlying Puerco and Torrejon formations is exposed. 

 Fossils are abundant and the stratigraphic relations of the beds absolutely 

 diagrammatic. It will be shown that dinosaurs, which are abundant in the Oio 

 Alamo beds ("Laramie" of the United States Geological Survey), are not 

 found above the marked erosional unconformity which separates the Puerco 

 clays from an underlying heavy conglomeratic sandstone with many volcanic 

 pebbles and much fossil wood. This unconformity may be traced for many 

 miles about the southern margin of the San Juan Basin and may represent an 

 important time hiatus. The position of the various faunal levels of the Puerco 

 and Torrejon will also be discussed, and measured section will be presented 

 showing their position with reference to the unconformity below the Puerco, 

 above which dinosaurs are not found. 



PHYLOGEXETIC DETELOPMEXT OF THE EEXACTIXELLID DICTYOSPOXGES, AS 

 IXDICATED BY THE OXTOGEXY OF AX UPPER DEVOXIAX SPECIES 



BY JOHX M. CLARKE 



At 4.30 the Society adjourned. 



