68 Royal Society. 



The purpose in this brief notice is not, however, to pursue tlirs 

 kind of research, but to put on record an application of our know- 

 ledge of the fact that vivid patterns are not presented by testacea 

 living below certain depths, to the indication of the depth, within 

 certain limits, of palaeozoic seas, through an examination of the 

 traces, of colour afforded by fossil remains of testacea. 



Although their original colour is very rarely exhibited by fossil 

 shells, occasionally we meet with specimens in which, owing proba- 

 bly to organic differences in the minute structure of the coloured 

 and colourless portions of the shell, the pattern of the original paint- 

 ing is clearly distinguished from the ground tint. Not a few exam- 

 ples are found in Mesozoic as well as in Tertiary strata, but in all 

 the instances on record, the association of species, mostly closely allied 

 to existing types, and the habits of the animals of the genera to 

 which they belong, are such as to prevent our having much difficulty 

 about ascertaining the probable bathyinetrical zone of the sea in 

 which they lived. 



But in palaeozoic strata the general assemblage of articulate, mol- 

 luscan and radiate forms is so different from any now existing with 

 which we can compare it, and so few species of generic types 

 still remaining are presented for our guidance, that in many in- 

 stances we can scarcely venture to infer with safety the original 

 bathymetrical zone of a deposit from its fossil contents. Con- 

 sequently any fact that will help us in elucidating this point be- 

 comes of considerable importance. 



Traces of colouring are rarely presented by palaeozoic fossils, and 

 the author knows of few examples in which they have been noticed. 

 Professor Phillips, in his * Geology of Yorkshire,' represents the car- 

 boniferous species, Pleurotomaria flammigera (i. e. carinata) and co- 

 nica, as marked with colour, and Sowerby has figured such mark- 

 ings in P. carinata and P. rotundata. In the excellent monograph 

 of the carboniferous fossils of Belgium, by Professor De Koninck of 

 Liege, indications of pattern-colouring are faintly shown in the 

 figures of Solarium pentangulatum, and distinctly in those of Pleu- 

 rotomaria carinata and Patella Solaris, 



In the cabinets of the Geological Survey of Great Britain are 

 some finely-preserved fossils from the carboniferous limestone of 

 Parkhill, near Longnor in Derbyshire. Among these are several 

 that present unmistakeable pattern-markings, evidently derived from 

 the original colouring. They are — 



Pleurotomaria carinata and conica, showing wavy blotches, resem- 

 bling the colouring of many recent Trochidce. 



An undescribed Trochus, showing a spiral band of colour. 



Metoptoma pileus, and 



Patella ? retrorsa, both with radiating stripes, such as are pre- 

 sented by numerous existing Patellidce. 



Natica plicistria, with broad mottled bands. 



Aviculo-pecten, a large unnamed species, with spotty markings on 

 the ribs in the manner of many existing Pectines. 



Aviculo-pecten sublobatus, Ph. } Beautifully marked with radiating, 

 well-defined stripes, varying in each individual, and resembling the 



