D^VONIATl>I ROCKS OIF CANADA WEST. 107 



adteT by observing, tbat in some instances, tlie transition from tlie 

 angnlar form to the circular or cylindrical form, is so gradual, that it 

 is difficult to detect the line of demarcation. One of his figured 

 specimens was collected on the shores of Lake Erie ; and as we have 

 many from the same locality which are unquestionably of the same 

 species as that represented by his figure 4 ffl, we have the means of 

 knowing with all desirable certainty precisely what form he had in 

 view when he prepared his description. Several of the specimens in 

 the collection of the geological survey from lot No. 6, con. 1, Wain- 

 fleet, are small pyriform masses three inches in height, and gradually 

 enlarging from a small base to the width of two inches in the upper 

 part. The cells open out on the surface obliquely, in an upward 

 direction, and, in fractured specimens, are seen to curve from the 

 vertical central axis of the mass outwards. The large cells are one 

 line or a little more in diameter, and the small ones of all sizes down 

 to one fourth of a line. The inner surfaces of the cells are rough- 

 ened by very numerous short projecting lamellae, which appear to be 

 the remains of the transverse diaphragms which have been destroyed 

 along the central part of the cavity. This character, of course, can 

 only be observed where the tubes are empty. The large tubes are 

 often perfectly circular, but in general they are more or less poly- 

 gonal, and surrounded by from five to nine smaller ones. On each 

 face of the small tubes, there is a single row of pores. When the 

 tubes are nearly equal, there are occasionally two rows of pores. I 

 have not yet seen a border round the pores as in F. Gothlandica, In 

 some of the tubes there are faint indications of longitudinal striae. 

 The figure 4 a given by Groldfuss does not exhibit the pores, but the 

 roughened interior of the cells and aspect of our specimens is so 

 perfectly represented, that there cannot be the least doubt as to the 

 identity of the species. 



Granting, therefore, that the small pyriform masses from Wainfleet 

 are of the species intended by Goldfuss, and taking our departure 

 from them as a starting point, there is, in the Museum of the G-eolo- 

 gical Survey, a perfect transitional series, from specimens two or three 

 inches to large pyriform masses eight inches in height and six inches 

 in diameter on the top. The cells in these large specimens are always 

 large, and very unequal in size at the smaller or basal extremity of 

 the mass, while above and on the top they become nearly equal, and 

 are upon an average smaller than they are below. When such speci- 



