186 Proceedings of the Boyal Physical Society. 



round the head only of the fish, so that it is generally that 

 portion which is preserved in the round. 



There is a special interest attaching to these Lower Old 

 Eed myriapods which would appear to be the oldest land 

 animals yet known, or, at least, described. They occur along 

 with Eucephalaspis at that place made classic by the writings 

 of Hugh Miller and others — " Balruddery Den " — in Forfar- 

 shire, and were in all probability alive when many Upper 

 Silurian forms of animals and plants were still extant. In 

 another matter they bear some slight evidence as to the 

 conditions under which the Lower Old Eed sandstone was 

 deposited, as they point to proximity to land, and give coun- 

 tenance to the theory, otherwise well supported, of that for- 

 mation having been laid down in an inland sea or lake. 

 Plants are found associated with the specimens in nearly 

 every case, and one specimen belonging to Mr Powrie, on 

 which the remains of four or five different individuals are 

 seen on the exposed surface, is nearly black with fragments 

 of land plants. 



To the biologist they are interesting, for they are simpler in 

 construction than any other described Chilognaths. The body 

 segments are all free, and each bears but one pair of legs, a 

 condition of things which is only to be found in the larvae 

 of their recent congeners. In this they are very unlike the 

 Carboniferous genera, which depart more widely from larval 

 forms than do recent adults, a circumstance which appeared 

 to Scudder, who did not know of these older forms, to be 

 anomalous and inexplicable.* 



The wide sternal plates of the Old Eed myriapods link 

 them on to the Carboniferous genera, and the broad lateral 

 forked spines of Eiiyhohcria armigera and E. ferox may be 

 looked on as the homologues of the lateral lamellae of Archi- 

 desmus. Our recent Craspedesoma Raulinsii has its lateral 

 lamellie set with two strong spines or bristles at their pos- 

 terior angles, much as in Eupholeria (PI. II., fig. 3). No 

 trace of frustra, such as occur in Xylohius, have been ob- 

 served, nor any foramina repiignatoria. The former could 



* See Scudder on Myriapods of the genns Eiqyhobei'ia (Meek and Worthen) 

 — American Jour, of Science^ vol. xxi., p. 186. 



