. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. No. 5. — Some C hazy an Sponges By Percy E. Raymond and Vladimir J. Okulitch Sponges are fairly common in certain Chazvan limestones in Ten- nessee, Virginia, the Champlain Valley, and the Mingan Islands. In the following pages brief descriptions of some of the more prominent species, with illustrations, are presented. No satisfactory method of the study or description of the more common Ordovician sponges exists. Although skeletal structure is observable in the better pre- served specimens, it is seldom possible to d
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. No. 5. — Some C hazy an Sponges By Percy E. Raymond and Vladimir J. Okulitch Sponges are fairly common in certain Chazvan limestones in Ten- nessee, Virginia, the Champlain Valley, and the Mingan Islands. In the following pages brief descriptions of some of the more prominent species, with illustrations, are presented. No satisfactory method of the study or description of the more common Ordovician sponges exists. Although skeletal structure is observable in the better pre- served specimens, it is seldom possible to determine the nature of the spicules, and more often than not, the thin slices reveal nothing of importance. In the present discussion, we have put most emphasis upon the gross structure, taking into account chiefly the outer form, the position of the canals, and the more obvious characteristics of the skeleton. These serve to define a number of rather easily recognized groups, and such a method of course facilitates identification. This work was started by the senior author several years ago, but for various reasons was not finished. It was taken up and completed by the junior author during his stay at the Museum of Comparative Zoology, at intervals in his more regular work on Paleozoic corals. This part of the work was done on a fellowship awarded by the Royal Society of Canada. The assembled material was restudied, paying attention both to the gross structure of the sponges and to the microscopic form of the spicules. It was found that although poor preservation tends to ob- scure the spicules, in many cases they can be distinguished both on the weathered surface and in thin sections. The majority of them con- tain tetracladine spicules of the Aulocopium type. It accordingly appears that they belong to the Aulocopidae. These sponges are included with the Aulocopidae Rauff, (Rauff, Palaeontographica, 40, 41, 1893-94 & 1894-95) rather than with the Anthaspidellidae Ulrich
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