56 Rev. P. B. Brodie on the Inferior Oolite and Lias 



1. That the sand-canal is intended from time to time to dis- 

 charge externally the fluid contents of the ambulacral system of 

 tubes. 



2. That the ambulacral or water-vascular system of those 

 Echinoderms in which it exists, is a modification of a part or 

 the whole of the so-called blood- vascular system of the Annulose 

 families in general. 



3. That in both the former and in the latter instances the 

 fluid contained in the vascular system is derived hy absorption 

 from the cavitary fluid. 



In a paper lately laid before the Royal Society I have described 

 an organ in the Annulose and Radiated classes, which I have 

 ventured for the present to call the " Segmental organ/^ and 

 which is to the "cavitary fluid'' what the madreporiform tubercle 

 in Asterias, and the cervical fissures in the Nemertidse, are to 

 the contents of the vascular system. Both are provisions for the 

 immediate and direct excretion of the entire body of the nutritive 

 fluids. These facts prove that as we descend the scale of animal 

 life, the mechanism of the physiological act of " secretion '' is 

 simplified in the ratio in which the fluids and solids of the living 

 body themselves are simplified ! 



I remain, Gentlemen, your obedient servant, 



Thomas Williams, M.D., F.L.S. 



VII. — Remarks on the Inferior Oolite and Lias in parts of North- 

 amptonshire, compared with the same Fot'mations in Gloucester- 

 shire. By the Rev. P. B. Brodie, M.A., F.G.S. 



Having, at a late meeting* of the Cotteswold Naturalists' Club, 

 given a viva, voce account of the Inferior Oolite and Lias in a 

 part of Northamptonshire; at the request of the Secretary, I 

 have prepared a more detailed description for our ' Proceedings.' 

 It is well known that certain beds in the Inferior Oolite in the 

 neighbourhood of Northampton have been extensively worked 

 for the ironstone which largely prevails in it thereabouts, though 

 I believe it is not now so generally used for oeconomical pur- 

 poses as it was formerly. This was certainly the case with 

 those quarries which I examined near Blisworth. They are not 

 worked to any great depth, and occupy the higher ground in the 

 district; the strata consist of sandy ferruginous oolitic stone 

 containing a few imperfect casts of shells, though the greater 

 part of the mass is unfossiliferous : the top beds are coarse, and 

 contain impressions of shells; the lower ones are more com- 

 pact, and are composed chiefly of ironstone. The Inferior Oolite 



* Held at Cheltenham in August 1856. 



