Reports and Proceedings. 131 



Thomas Brown, of Stewart on, in the Upper Coal Measures of Kil- 

 maurs. It occurs in a nodule of ironstone, coiled up somewhat in 

 the form of the letter J, and is about two inches in length. Each 

 segment of the body (of which there are upwards of thirty) bears a 

 slightly raised wart, which indicates the position of the tracheal 

 openings, while to the sternum of each segment a pair of slender 

 feet appear to have been articulated. These feet can distinctly be 

 seen to be composed of several articuli, as in the recent Myriapoda. 

 No soft-bodied annelide would be preserved in this condition, the 

 body-rings of worms which the author had examined from Soleii- 

 hofen, for example, being indicated rather by a stain upon the slab 

 than by any actual relievo evidence of their presence, as shown in 

 the Kilmaurs specimen. It may therefore be concluded that this 

 fossil possessed a chitinous exo-skeleton, sufficiently firm and strong 

 to leave the impress of its numerous and well-marked articuli in the 

 soft clay in which it was entombed. Mr. Woodward stated that 

 without further evidence it would be rash to describe this fossil as 

 specifically distinct from that discovered by Dr. Dawson ; but it was 

 important to record this instance as the first discovery of Xylohius in 

 Britain. Preserved with it, in the same nodule, are a perfect pinnule 

 and several fragments of a Fern, the Pecopteris ahbreviata of Brong- 

 niart. It is extremely interesting to find this presumed terrestrial 

 Myriapod, both here and also ia America, associated with land 

 vegetation. The evidence of land-conditions to be derived from 

 associated fossils, must not, however, in this case be too strongly 

 relied upon, as in the same bed of nodular ironstone are likewise 

 found King-crabs and other undoubted marine organic remains. 



The second portion of the author's paper (which will be pub- 

 lished, with accompanying plates, in the next part of the Society's 

 Transactions) was devoted to the re-description (1) of Belinurus 

 trilobitoides and PrestioicJiia rotundata, two species of Limuloid Crus- 

 tacea, also found in the nodular ironstone of Kilmaurs, from examples 

 of which he had been enabled to detect several important structural 

 characters not previously noticed ; and (2) Pygocephalu& Cooperi, 

 Huxley, from the same locality. In conclusion, he stated, having 

 frequently observed, in the examination of various genera and species 

 of fossil Crustacea, that certain species in dying always appear to 

 have assumed a particular position. Certain others, after death, 

 appear always to break up in a systematic manner. Ceratiocaris is 

 generally found in the Upper Silurian of Lesmahagow, with its 

 tail in its mouth. Trimerocephalus, in the Devonian of Newton, 

 always has its head directed towards its tail, and detached. Again, 

 one species of Crustacea always occurs with the dorsal aspect 

 exposed upon the matrix ; another as invariably presents the ventral. 

 Thus the specimens of Pygocephalus present the ventral aspect ex- 

 posed to view, whilst the dorsal adheres as firmly as possible to the 

 matrix. 



2, On the Sections of Igneous Eocks on the Eye, Ayrshire. By 

 Mr. E. Whyte Skipsey. — Mr. Skipsey described the th?:ee principal 

 sections which are observed in descending the bed of the stream, 



