240 



Scientific Geology. 



irregularly ramified masses of flint, or siliceous slate, from half an 

 inch to an inch in diameter. I could not resist the impression, that 

 this siliceous matter may have taken the place of a zoophyte : al- 

 though I have seen no certain evidence of organization. (No. 267.) 

 But if the specimens that have been described are Gorgoniae, there 

 is certainly presumptive evidence that other zoophytes would be found 

 in the same rock. 



Radiaria. 



Under this name I have a specimen, perhaps still more remarkable 

 than the last, to introduce. It is from the fetid limestone in West 

 Springfield. Plate XII. Figs. 29, 30, 32, and 33, are intended to 

 convey an idea of the most important varieties of this petrifaction, 

 which I have hitherto discovered. Fig. 33 exhibits its most common 

 form. This is composed of numerous cylindrical bodies, usually 

 less than half an inch in diameter, and several inches long, running 

 in a parallel direction through the limestone. On breaking them 

 transversely, they are seen to consist of concentric layers of carbon- 

 ate of lime, of various shades of color ; the outside of the external 

 layers (and, indeed, more or less so of the others,) being covered 

 with small warty protuberances ; but showing no marks of trans- 

 verse septa. Not unfrequently a small perforation occupies the cen- 

 ter of the cylinder ; and at other times it is occupied by calcareous 

 spar, which probably entered by infiltration. A radiated structure is 

 sometimes not obvious : but if I do not greatly mistake, it is evident 

 Avhen specimens are newly fractured crosswise. (Nos. 268 to 277.) 



Fig. 32 exhibits one of these cylinders, terminated by a spheroidal 

 head, and covered over with the warty protuberances that have been 

 mentioned. 



Sometimes these cylinders enlarge and several of them (frequently 

 three) become united, so that the outer layers enclose the whole : as 

 is shown in Fig. 30. 



In one or two instances, numerous small cylinders become united 

 in this manner, and form a rather confused mass in the center, sur- 

 rounded, however, by distinct layers. In this case a great enlarge- 

 ment takes place, as in Fig. 29. The lower part of that specimen, 

 which cannot be seen in the sketch, exhibits numerous small and dis- 

 tinct tubes, which, by extending an inch or two, become blended in 

 the confused mass that occupies the central parts, as seen on the up- 

 per surface in this figure. 



