NO. 5 ORDOVICIAN BRYOZOA — BOARDMAN 7 



of Minneapolis. All the incrusting growth inckided in the thin section 

 appears to be overgrowth conspecific with the supporting branch of 

 B. varium. Species characters of incrusting forms and overgrowths 

 are generally extremely variable, owing at least in part to compensa- 

 tions made necessary in covering rough, irregular surfaces. It is pos- 

 sible to say only that the overgrowth on the specimen of B. varium 

 could be within the morphologic range of the other primary types of 

 S. ovata. The other primary types of 5". ovata incrust other genera 

 of Bryozoa and so are true incrusting growths. A detailed study of 

 many topotypes is necessary to clarify the relationships between the 

 two species. On the basis of comparison of presumed generic char- 

 acters, however, Stromatotrypa is here considered to be a junior sub- 

 jective synonym of Batostoma, and 5". ovata is reassigned to 

 Batostoma. 



Two other species in the National Museum collections have been 

 assigned to Stromatotrypa. The primary types of S. glohularis Ulrich 

 and Bassler, 191 3, Keyser limestone member of the Helderberg 

 limestone. West Virginia and Maryland, are badly silicified and re- 

 sectioning of the types has not revealed sufficient characters to re- 

 assign the species. 6^. frondosa Loeblich, 1942, from the Bromide 

 formation, Oklahoma, is closely comparable with B. prosseri Cumings 

 and Galloway, 191 2, and both species are placed in Batostoma with 

 some uncertainty. 



BATOSTOMA IMPLICATUM (Nicholson) 

 PI. I, figs. 1-5; pi. 2, figs. 1-4; pi. 7, fig. 2 



1881. Monticulipora (Heterotrypa) implicatum Nicholson, The genus Monti- 



culipora, p. 147, pi. 2, figs. 7-76, text fig. 27. 



1882. Batostoma implicatum (Nicholson), Ulrich, Journ. Cincinnati Soc. Nat. 



Hist., vol. 5, pt. 2, p. 256. 

 1908. Batostoma implicatum (Nicholson), Cumings, Indiana Dept. Geol. and 

 Nat. Res. 32d Ann. Rep., p. 774, pi. 7, fig. 7 ; pi. 8, fig. 2. 



Type data. — The species was first named in a faunal list by Ulrich 

 (1880, p. 12) but no indication, definition, or description was included. 

 The list dealt with the fauna about Cincinnati, and Ulrich reported the 

 species from the 100- to 200- foot interval above the low- water mark 

 of the Ohio River. This interval now forms the greater part of the 

 Southgate member of the Latonia shale of the Eden group (Bassler, 

 1906, p. 8; 100 to 220 feet above the low-water mark). In 1881, 

 Nicholson published a description of the species based on specimens 

 received from J. M. Nickles of Cincinnati, a close associate of Ul- 



