I860.] on the Devonian Fossils of Devon ^ Cornwall, 367 



this principle as a guide, it might have been expected that species 

 having a wide geographical distribution would be equally remarkable 

 for their specific longevity ; and that such as were confined to a 

 limited area disappeared from the stage of existence in a comparatively 

 short time. In the case under consideration, however, the facts do not 

 harmonise with such conclusions : Favorites Goldftissi, found in the 

 most widely separated parts of the earth, appears to have commenced 

 and closed its existence within the limits of the Devonian period ; 

 whilst Chonophyllum perfoliatum, confined geographically, so far 

 as is at present known, to the British area, was a member of the 

 Silurian as well as of the Devonian fauna. The gigantic size of some 

 of the corallums — Favorites Goldfussi has been found upwards of two 

 feet in diameter — seems to imply that the climate of European lati- 

 tudes was warmer, or at least that the winters were less cold, during 

 the Devonian age than at present. The fossil coral reefs of Torquay 

 and Ogwell suggest that the old Devonian sea was not at first of pro- 

 found depth, that is if then as now the reef-building zoophytes did not 

 labour at depths exceeding 25 fathoms ; whilst the facts that some of 

 the limestone sections reveal an aggregate thickness greatly exceeding 

 this depth, and that every stratum in them is richly charged with fossil 

 corals, seem explicable only on the supposition that the area was one 

 of slow, gradual, and long continued subsidence. 



The Pterygotus, the " seraphim " of the Scotch quarrymen, does not 

 occur in Devonshire or Cornwall. With one exception only, the crus- 

 taceans are all trilobites. Amongst them that named Trimerocephalus 

 IcBvis occurs under somewhat remarkable circumstances. So far as is 

 at present known, it has been found only in one locality, namely, on 

 the flanks of a hill called Knowles, near Newton Abbott, in South 

 Devon, and no other fossil of any kind has been found there ; on this 

 point, our present knowledge is expressed by saying, " there is but one 

 locality for the fossil, and but one fossil for the locality." Many 

 hundreds of specimens of it have been found, and a very considerable 

 number of them have passed through the hands of the speaker ; he knew 

 of but two instances in which the head was found attached to the thorax. 

 On splitting a stone, and thereby disclosing one of these trilobites, ex- 

 cepting in the two cases just named, the head was not visible ; or, what 

 was very much more frequently the case, one half of the stone was 

 found to contain the thorax and tail united, and the impression of the 

 head ; whilst in the other half were found the head and the impression 

 of the body, and always in such a way as to show that the head had 

 been severed from the body, removed a short distance from it, (as if 

 drawn or pushed forward,) and inverted ; there were never any indica- 

 tions of eyes, and not unfrequently the tail appeared somewhat trunc- 

 ated, as if its terminal margin were slightly folded under. It is clear 

 that an inversion of the head might have been effected, either by a 

 semi-rotation at right angles to the axis of the body, or in the direction 

 of that axis ; but as the anterior margin of the head was always found 

 nearest the thorax, it is clear that the motion had been of the latter 



