Richmondian Trilobites from Akpatok Island

Abstract

The Trilobites, which include one new species, here described were collected by the writer from Akpatok Island 1 in Ungava Bay while on the Oxford Hudson Straits Expedition in 1931. The single species of graptolite found there has already been described 2; in addition to the trilobites, there are brachiopods, corals, crinoids, gasteropods, cephalopods, and ostracods, which still await identification. The following species of trilobites are here recorded: Isotelus iowensis Owen, Megalaspis beckeri Slocom, Illaenus eucentrus Troedsson, Illaenus groenlandicus Troedsson, Bumastus sp., Calymene cf. fayettensis Slocom, Calymene cf. meeki Foerste, Encrinurus sp., Ceraurus horridus Troedsson, Ceraurus tuberosus Troedsson, Ceraurinus icarus (Billings), Ceraurinus daedalus sp. nov., Pterygometopus fredricki Slocom.

Part I. Montoya and related colonial corals. Part II. Organisms attached to Montoya corals

“…Septa develop, it is true, but they are never more than discrete columns of spines; with broadening of the coenenchyme, the "costae," which resemble septa extending from the periphery of the corallites, are specializations within the walls, which are here, as in Nyctopora, true common walls, and their similarity to septa is regarded as adventitious. The objection of Cox (1936) to recognition of a true coenenchyme here is not valid, and is opposed by the development of clear walls around the corallites in the more advanced types, a matter that his interpretation does not explain.…”

“…The present study suggests also that recognition of variation in colony form, and the possibilities of ecological control, have resulted, particularly in these colonial corals, in what is almost certainly an excess of conservatism in regard to the recognition of species. The extremely conservative treatment of Calapoecia by Cox (1936) has already been noted. There are many similar examples, such as the previous broad inclusion of most Ordovician favistinas as Favistella alveolata, the loose, broad definition of Favistella discreta Foerste, and the general recognition in North America of only one species of Protarea and of Protrochiscolithus; our material suggests, moreover, that the current recognition of still other species, notably in Foerstephyllum, may still be far too broad.…”

“…Inquiry addressed to Dr. 0. M. B. Bulman concerning some of the forms resulted in the loan of the unworked part of the collection, with significant specimens of the Calapoecias, which Cox (1936) had studied. Much labor was saved the writer, for sections of the previously unstudied colonies were made at the Sedgewick Museum.…”

“…However, once the colony has grown to develop mature individuals of normal size, budding individuals approach this size so rapidly that there are never enough to cause confusion. Cox (1936) concluded that all species of Calapoecia were one, because of the similarity of early stages of colonies; the perplexity was increased by budding individuals in later stages. It seems, however, that in doing so he overlooked the significance of ontogenetic progression, and of the variation to be expected in the initial phases of colonies on the one hand and that of budding individuals in later growth stages on the other.…”

“…There has been much confusion as to the distinctness of the species; Cox (1936) claimed that there was only one species, and Bassler (1950) Recognition of only a single species in the genus rests upon two assumptions: (1) that the species intergrade, intergradation being shown within colonies in some instances, and (2) that corallite size and colony size are features of no significance. The first contention is true, but ignores matters of coral ontogeny that are deserving of consideration.…”