28 PROCEEDINGS OF THE 



Magazine. Mr. Rofe's specimens are supplemented in the 

 National Collection l>y many others from the Derbyshire lime- 

 stones, all pointing to one conclusion, that the coral in question 

 was one of the most important agents in affecting distortion and 

 enlargement in the Crinoid columns of the Derbyshire and York- 

 shire Carboniferous area. Some idea of this may be formed 

 when I say, that I have now before me more than fifty well- 

 marked examples. In PI. II. tig. 12 a may be seen the end of a 

 stem with the petaloid canal, and the articular crenulations of the 

 ossicle there exposed quite normally. Within the space of about 

 eight or nine ossicles, or one inch vertical, the diameter has 

 increased from seven lines, the measurement at the smaller end, 

 to eleven lines, or nearly one inch, the actual breadth of the 

 original stem at this point (PL II. fig. 12), exclusive of the coral 

 and subsequently deposited matter, being as near as possible six 

 lines. The individual had therefore increased in thickness on each 

 side of the stem, through the action of the coral, between two 

 and three lines. The action of the Gladochonus in attaching 

 itself to the Crinoid stem is peculiar and characteristic. After 

 the first attachment was made, it evidently grew laterally right 

 and left, throwing off its bud-like calices, and ultimately sur- 

 rounding the stem, as it were, with a band or belt (PI. II. 

 fig. 11). By this means a series of projecting corallites were 

 left standing out from the stem like the spokes of a wheel from 

 the axle, and in overcoming and surrounding which the Crinoid 

 deposited sufficient substance to cause the swellings we are now 

 investigating. The amount of the envelopment varied in different 

 specimens. In some complete investment has taken place, in 

 others partial enclosure only has gone on, whilst, in a third ex- 

 ample, the apertures of the calices of the coral only are left. 

 In this state the true nature of such openings is not easily deci- 

 pherable, and it is only on making these microscopic sections 

 that the cause becomes apparent. On examining such a section 

 (PI. II. figs. 13 and 14), it will be observed that complete encircling 

 of the stem has taken place, the corallites all being connected by a 

 common tube. From this it follows that the enclosing Growth of 

 the Crinoid took place from above or below, or both. The stems 

 infested with Gladochonus appear to have experienced great incon- 

 venience from its presence, if we may judge from the contorted, 

 gnarled, and uncomfortable appearance most of the specimens 



