ABSTRACTS OF PAPERS 151 



lated by Girty with the Gschelian. Overlying tlie conglomerates are Middle 

 Triassic beds. Where seen, the conglomerates had not weathered down and it 

 was not possible to obtain loose boulders which might show scratches. Facet- 

 ted boulders occur in the conglomerate, however. It will probably be found 

 that this is a true glacial deposit and to be correlated with the conglomerate 

 described by Cairnes near the Alaskan-Canadian boundary. A conglomerate 

 similar to that described above underlies the Middle Triassic rocks of Dall 

 Head, Gravina Island, and may prove of the same age and of similar character. 



In the String ocepJialus limestone zone of the Middle Devonian small facetted 

 pebbles up to 2^2 inches in length are of fairly frequent occurrence at one 

 locality on the west coast of Prince of Wales Island. In Freshwater Bay and 

 in Port Frederick, which lie near the northern end of Chicago ff Island, some 

 250 miles to the north, conglomerates occur in the Middle Devonian. Rounded 

 boulders up to 2 feet in diameter were seen. They are very unlike noi'mal 

 sedimentary conglomerates. Should the boulders in the Devonian prove gla- 

 cial, a somewhat different origin would probably be postulated for the con- 

 glomerates themselves. These are thin, ranging in thickness up to 25 feet or 

 so, and would be more easily explained perhaps as consisting of berg-borne 

 material, though glacial in origin. Bottoms of a similar nature are even now 

 to be found in the channels of southeastern Alaska. 



Throughout the Paleozoic section in southeastern Alaska are vast thick- 

 nesses of volcanic material, tuffs, breccias, and flows. Considering the sedi- 

 ments as a whole, climatic conditions through the Paleozoic do not seem to 

 have been very different from those of comparatively recent times and physical 

 conditions may have been very nearly the same. 



Some of the results of a monographic study of American Tertiary 

 Gyclostome bryozoa were presented by the junior author in the following 

 paper, which was illustrated by lantern slides and specimens and dis- 

 cussed by Doctor Grabau. 



PRINCIPLES OF CLASSIFICATION OF GYCLOSTOME BRYOZOA 

 BY F. CANU^AND R. S. BASSLER 



(Abstract) 



During the preparation of a monograph on American Tertiary bryozoa the 

 authors extended their study of the Cyclostome bryozoa to the Cretaceous and 

 recent forms in order to arrive at some definite data for the natural classifi- 

 cation of thi§ group. As the zooecial form is practically the same in all the 

 Cyclostome bryozoa, it is impossible to base a classification on this as is done 

 in the other groups of this class. Hitherto the classification of the Cyclo- 

 stomata has been based almost entirely on the form of the colony or zoarium, 

 although it has always been realized that this was a very unnatural basis. 

 The present authors have found that the ovicell, the marsupium-like organ 

 which is developed on Cyclostome bryozoa, affords a natural basis of classifica- 

 tion and the families and genera group themselves according to the position 

 and form of this organ. 



XII— Bull. Geol. Soc. Am., Vol. 29, 1917 



