7(>4 



Report of the State Geologist. 



with the second mineral layer; that the grooves were tilled with phosphate of 

 lime and covered by the sculptured outer layer with an underlying thin film 

 similar in appearance to the second layer. The groove, therefore, appeals to 

 be altogether an expansion of the second layer of the wall. A diagrammatic 

 section of the groove at the angle of 0. gracilis is given in Plate II, figure 4. 



The reasons which the writer has for regarding the cuneiform appen- 

 dages of C. gracilis, and the bodies attached to Troclwn&ma, etc., as remains 

 of young individuals of < '. graciUs are as follows: 



1. Wherever an appendage is preserved completely it shows four 

 divergent grooves, such as would form the edges of a pyramid, with about 

 the same angle as the older shells of 0. gracilis (PI. I, figs. 2, .">, PI. II, 

 fig. 1). Some apparently show only three grooves, but investigation w ill 

 generally bring out the fact that the fourth is divergent from the plane of the 

 others and hidden in the matrix. Generally, however, the whole fossil 

 appears only as a cuneiform film between two thick edges, w hich are formed 

 by two coinciding grooves, while the two originally vertical faces have been 

 folded inward between the horizontal ones or partly bulge out from between 

 them (PI. I, fig. 1, a). Some appendages show even but one groove; 

 the proximal parts of the other grooves, how ever, are also ordinarily traceable 

 into the matrix (PI. I, hg. 2). It is to be concluded from this that the 

 complete appendages contained grooves which originally did not lie in one 

 plane. 



2. The four grooves show exactly the same structure and composition 

 as those of C gracilis, i. e., the V-shaped section, the filling with milk white 

 phosphate of lime, the extension of the carbonaceous sculptured surface film 

 over them, and especially the very characteristic and easily discerned trans- 

 verse ridges of the side w alls of the groove. (Cf. PI. I, figs. 1, b, 2, 5; 

 PI. II, figs. 1, 7.) 



3. The space between the grooves of the appendages is generally 

 perfectly smooth, thus indicating that between them was a connecting wall 

 which is now lost. However, in many places the tender carbonaceous surface 

 film is still preserved. Where this is the case the longitudinal ribs, as well 

 as the characteristic undulating transverse wrinkles, are clearly discernible, as 

 indicated in Plate I, figures 1, 2, and Plate II, figures 1, 7, at s. 



4. The carbonaceous cup-shaped bases, by w hich the supposed young 

 Conula/ricB are attached t<» the older individuals, are exactly similar to those 

 of some larger fossils which can be safely referred to (J. gracilis, and 

 especially similar to the basal cups of the two important specimens repro- 



