Cincinnatiaii and Lexington Fossils 33 



sible to distinguish these extremes of form as distinct species, or 

 even as varieties. As a matter of fact, within certain Hmits, the 

 species varies considerably in form at the same locahty, in the 

 same strata. At a distance of about 12 mm. from the beak there are 

 abouc 7 radiating striae in a width of 3 mm. 



Catazyga headi is represented along the northern line of out- 

 crop of Cincinnatian strata, in Ohio, Indiana, and northern Ken- 

 tucky, by a closely similar form. For this form, Air. E. O. Ulrich 

 proposed the name Glassia schuchertana, in the American Geologist, 

 vol. I, p. 186, in 1888, and added the following comments: 



This name is proposed for the shell figured and described by Meek in 

 volume l,Olno Paleontology, page 127, plate XI, figures la-Id, under the name 

 Zygospira Hcadi, Billings (sp.)- Recent investigations of excellent material, 

 belonging to Mr. Charles Schuchert's extensive collection of paleozoic brachi- 

 opods, show that our shell is distinct from the Canadian form, and that it pos- 

 sesses internal spires arranged precisely as in Davidson's new genus Glassia. 

 Some of the specimens show further that the radiating striae which usually 

 mark the surface are often very obscure and in rare cases entirely absent. 

 Such smooth examples were collected near Versailles, Indiana. 



Numerous specimens collected since the preceding lines were 

 published indicate that well preserved specimens are not smooth 

 but are covered with radiating lines which may be traced as far as 

 the tip of the beak, as is also the case in typical specimens of 

 Cata::yga hcadi from the type locality in Canada. Smoothness 

 results from weathering or exfoliation, and usuallv is noticed only 

 in small specimens or toward the beak of larger specimens, although,, 

 occasionally, specimens 15 mm. in length wliich have been more or 

 less weathered or exfoliated appear smooth until held transv^ersely 

 to the direction of some strong beam of light. 



Specimens from Cincinnatian areas vary considerably in out- 

 line, as is true also in case of the specimens from Canada. Some 

 are broad and some are narrow, resembling typical Catazyga headi 

 and its variety borcalis, as illustrated by the Ohio specimens figured 

 by Hall and Clarke, 'but these forms are always intermingled in 

 the same strata and can scarcely be said to represent even varieties. 

 The subquadrate appearance of the shell, when seen from the 

 brachial side, is due chiefly to the considerable lateral extension 

 of the hingeline. and this is noticed even in the more narrow forms. 

 The comparative straightening of the lateral outlines is shown 

 chiefly bv the broader specimens, but this is not a constant feature. 

 In attempting to distinguish between the Cincinnatian specimens 



