l6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 



Discussion. — A direct relation exists between the progressive 

 broadening of the U-shaped pattern of the zooecial wall laminae and 

 the amalgamated appearance of the walls in tangential sections. In 

 the early part of the exozone the laminae are V- or sharply U-shaped 

 and the resulting appearance of walls in the tangential view is inte- 

 grate or narrowly amalgamate. As the zooecia become older and 

 grow distally, the ends of the laminae at the bottom of the U lie in 

 the plane of a tangential section to form the amalgamate band of 

 structureless or granular-appearing skeletal material in the tangential 

 section. Thus, as that U-shaped configuration broadens and takes up 

 an increasing proportion of the wall thickness as the zooid grows 

 older, the amalgamate band becomes broader and shallow tangential 

 sections of older zooecia are broadly amalgamate. 



Genus AMPLEXOPORA Ulrich 



1882. Amplexopora Ulrich, Journ. Cincinnati Soc. Nat. Hist., vol. 5, pt. I, 



p. 154; pt. 2, p. 254. 

 1890. Amplexopora Ulrich, Illinois Geol. Survey, vol. 8, pp. 377, 450. 

 1904. Amplexopora Ulrich, Ulrich and Bassler, Smithsonian Misc. Coll., vol. 47, 



No. 1470, p. 41. 

 1908. Amplexopora Ulrich, Cumings, Indiana Dept. Geol. and Nat. Res., 32d 



Ann. Rep., p. 739. 

 1920. Acanthotrypella Vinassa de Regny, Atti Soc. Ital. Sci. Nat., vol. 59, 



p. 221. 

 1935a. Acanthotrypella Vinassa de Regny, Bassler, Fossilium catalogus, I : Ani- 



malia, pars 67, p. 41. (Considered a junior subjective synonym of 



Batostoma.) 



Type species. — Atactopora septosa Ulrich, 1879, by subsequent 

 designation herein. E. O. Ulrich published a paper entitled "Ameri- 

 can Paleozoic Bryozoa" in parts in the Journal of the Cincinnati 

 Society of Natural History. The first part is dated October 1882, 

 the second part December 1882. In part i, Ulrich established the 

 genus Amplexopora with a brief definition (p. 154). In part 2 

 (p. 254) Ulrich described "A^nple.ropora cingulata, n. gen. et sp. 

 (Plate XI, figs. 5-5b) Generic char., ante p. 154." In remarks 

 following the description of A. cingulata Ulrich states, "The species 

 above described I regard as the type of the genus, Amplexopora, 

 proposed by me in the last number of the Journal, p. 154." 



In part i, Ulrich preceded his taxonomic section with a discussion 

 of morphology in which he cited four names of species of Amplexo- 

 pora. Two of the names are here considered to have been nomina 

 nuda, and two valid, as follows : 



One of the nomina nuda, "Amplexopora variabilis, Ulrich" (1882, 



