Bulletin Volume 77 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1911 edition. Excerpt: ... 73 a is especially interesting in illustrating not only the terminal points of attachment but also a large lateral socket. As noted in a previous description, this species and Helopora divaricata are liable to be confused. Comparison of figures 72 and 73 will show differences in zotncial characters, but the best and surest method of distinction is the discovery of a primary segment of the Arthroclema bearing the lateral articulation. Occur-rence.--The isolated segments of this species are abundant in the N ematopora bed of the lower Trenton limestone at Cannon Falls and St. Paul, Minnesota. In Russia the species so far has been observed only in the Glauconite limestone (B2) at Reval, Esthonia (Cat. No. 57247, U.S.N.M.). Represented in the collections of the British Museum by specimens from American localities. Genus SCEPTROPORA Ulrich. Sceptropora ULRICH, American Geologist, vol. 1, 1888, p. 228; Contr. Micro--Pal. Cambro-Sil., pt. 2, 1889, p. 46; Geol. Surv. Illinois, vol. 8, 1890, p. 400; Zittel's Textbook of Paleontology (Eng. ed.), 1896, p. 281.--SmrsoN, Fourteenth Ann. Rep. State Geologist of New York for the year 1894, 1897, p. 548.--NIoKLEs and BASSLER, Bull. 173, U. S. Geol. Surv., 1900, p. 43. Sceptropom was founded upon a single species, S. facula from the Richmond rocks of Manitoba, Canada, but has since been noted in these strata at many other localities. The discovery of numerous undoubted examples of S. facula in the Borkholm limestone is in line with other evidences showing the wide distribution of this Richmond fauna. The generic characters of Sceptropom are as follows: Zoarium of segments which become much expanded in their upper portion and. at the top have a socket for the articulation of the next segment; lower...