On some Fossil Myria'pods from Forfarshire. 185 



All the specimens studied, with the exception of the one 

 from the Jermyn Street collection (fig. le), have the horny 

 material of the test still preserved, and still retaining the 

 deep brown colour. The dorsal scutes must have been of 

 considerable consistence. The animals are not preserved in 

 the round like those found in ironstone nodules or in Sigil- 

 larian trunks where fossil myriapods have usually been 

 hitherto obtained; but they occur as hollow flutings, and 

 the legs, antennae, and the lateral lamelhe are found in the 

 same condition. The reason for this seems to be that the 

 dead gaily worm, when borne to its watery grave, still re- 

 tained its rounded form, and on sinking to the bottom made 

 a slight depression on the sandy mud. At length, being 

 entirely enveloped in sediment to a considerable depth, and 

 its perishable organs becoming decomposed, the pressure of 

 the superincumbent mud and w^ater was sufficient to make 

 the tubular body to collapse; but as it had been already 

 dimpled into the underlying layer, instead of being flattened 

 out it became folded together into a double-walled gutter, 

 the concave side of which was originally the convex side of 

 the animal that lay uppermost. The legs being also tubes 

 are treated likewise, while the lateral lamellae, being blind 

 sacs, now show as more or less circular pits. In the case of 

 those preserved in ironstone nodules, they have been de- 

 posited in mud in a similar manner to that already de- 

 scribed, but before the pressure was sufficient to bring about 

 the collapse, the body of the animal has acted as a nucleus, 

 round which the saline waters have deposited the iron and 

 lime carbonates, and the grains of mud having been thus 

 cemented together into a firm consistency, the remains of the 

 animal have been protected and preserved in the round. 

 Excellent examples of both effects are seen where fish have 

 been partially enveloped in nodules. The portions within 

 the nodules stand out in relief, while those parts which 

 extend into the ordinary shales beyond are pressed flat. The 

 otoliths of the fish appear to act as the nuclei, round which 

 salts of iron and lime gather, or in many cases to have 

 afforded the lime carbonate which has formed a nodule 



