154 Royal Society. 



(3.) The respiratory movements of each segment of the trunk are, 

 in some measure, independent of those of the rest, although in the 

 perfect insect they concur in all the segments. They continue to 

 be performed, though feebly and slowly, in separated segments, pro- 

 vided their nervous cords and ganglia are entire : and they may be 

 abolished in single and successive segments by the local action of 

 chloroform. 



(4.) The removal of the head, including the supra- and sub-oeso- 

 phageal ganglia, does not, like the removal of the medulla oblongata 

 of the vertebrate animal, put a stop to the respiratory movements of 

 the insect ; but it diminishes their frequency and force, and deprives 

 them of all influence of the will and of mental emotions. 



(5.) The shock inflicted by the sudden destruction of the head, or 

 of the terminal part of the abdomen, generally stops all the respira- 

 tory movements of the insect for a time, and much enfeebles them 

 during the remainder of its life. 



(6.) The general tendency of the observations is to corroborate 

 the opinion of the self-sufficiency of the several ganglia for the 

 movements of their appropriate segments, and, thus far, to maint&in 

 the belief in their essential independence. At the same time, the ob- 

 servations on the diffused influence of shocks accord with those of 

 the coordinate similar movements of all the segments, in proving 

 their close mutual relations and mutual influence. 



*' On the Structure of some Limestone Nodules enclosed in Seams 

 of Bituminous Coal, with a Description of some Trigonocarpons con- 

 tained in them." By J. D.Hooker, M.D.,F.R.S., andE. Binney, Esq. 



The authors first describe the occurrence of the limestone nodules, 

 which form a continuous bed in the centre of a thin seam of bitumi- 

 nous coal in the lower part of the Lancashire coal-field. The no- 

 dules were of various sizes, some weighing many pounds, and caused 

 the coal to bulge out both above and below them, and they were 

 found to be entirely composed of vegetable tissues converted into 

 carbonate of lime and magnesia. Their formation is supposed by 

 the authors to be due to infiltration of water through the superin- 

 cumbent shales, which were full of fossil shells supposed to be of 

 marine origin, and the aggregation of the mineral matter round 

 centres of vegetable remains. The chemical constituents of the 

 nodules were found to be carbonates of lime and magnesia, sesqui- 

 oxide and sulphate of iron, with a little carbonaceous matter. 



The probability of these nodules representing an average sample 

 of the vegetable constituents of the surrounding coal is then dis- 

 cussed, and attention is drawn to the very great interest and import- 

 ance that would attach to them were such a view substantiated, as 

 showing the exact nature of the association of plants which is 

 capable of conversion into bituminous coal. 



All the plants contained in the nodules were common in other 

 parts of the coal formation, viz. Culamodendron, Halonia, SigiUaria, 

 Lepidodendron, Stigmaria, Trigonocarpon, Anabothra, and others ; of 

 these the first-named genus occurred in the greatest abundance and 



