OF THE CAKBONIFEROUS STBATA. 



197 



free. My specimen figured in plate II. fig. 2, twice the natural 

 size, is from the limestone of the upper coal measures at 

 Ardwick. It is very like the shell mentioned by Professor 

 John Phillips at p. 88 of the Silurian Systeinj, previously 

 quoted, but larger in size. This author classed it with one, 

 if not both of the two species of spirorhis before mentioned, 

 and considered it as merely a specimen of more advanced age. 

 However, I have not met with any graduation of the spirorhis 

 into serpula either in recent or fossil specimens. The com- 

 mencement of the fossil shell in its first volutions is like 

 that of the spirorhis, but it then extends into a free tube like 

 vermilia. My specimen is three-tenths of an inch in length, 

 and one-twentieth of an inch in diameter at the broadest 

 portion of the shell. It is covered with irregular striae, placed 

 rather oblique to the axis of the tube, which is cylindrical. 

 From its characters and the places where it is found, both 

 differing from those of the spirorhis, I propose to call it the 

 serpula carhonarius. It resembles serpula more than any- 

 thing else ; and I have not yet found it attached to fossil 

 shells or plants like the spirorhis. 



The two species of spirorhis described in this paper, from 

 their external characters and the places where they are found 

 attached to the surfaces of shells and plants, lead strongly to 

 the conclusion that they belonged to parasitical annelids like 

 the common spirorhis, (serpula spirorhis of Penn. Brit. Zool., 

 No. 155, tab. 91, fig. 155.) But I am bound to state that I 

 have seen a specimen of a fern from the liancashire coal field 

 belonging to Mr. Matthew Dawes, F.G.S., with several shells 

 not to be distinguished from the small species previously 

 described embedded in the substance of the fossil. In my 

 own cabinet there is a specimen of a small sigillaria from the 

 roof of the Riley Mine at Captain Fold near Heywood. 

 The substance of this fossil is clay ironstone, but the epider- 

 mis of the plant is converted into coal. Under the coaly 

 envelope are numerous specimens of a shell like the spirorhis 



