43 



Orthids, that abounded in paloeozoic seas. Before recent researches brought 

 this bed to light, scarcely a couple of Brachipods were known in the whole 

 Upper Lias ; now, thanks to Messrs. Bouchard, Datudson, Mooee, and the 

 Deslongchamps, more than thirty species have come to our knowledge. In 

 truth, it forms a notable example of "recurrency," — one of those special 

 cases that bear so strangely on the generalizations of the palaeontologist, 

 namely, that in all times and epochs, continuity of land, of sea, and 

 sea-depth, produce continuity or extension of life. And whenever there is 

 discontinuity or separation of land or sea, the opposite sides of the barrier 

 are inhabited by different races. (Quarterly Jour. Geo. Soc, v. xv. p. 294.) 

 "We must not pause, tempting though it be, to speculate. To describe this 

 bed. — Its constitution is a fine sandy friable shale, the particles so 

 comminuted, that it may be crushed between the fingers. Touching the 

 organic contents, they will be seen, by reference to my incomplete list, 

 to embrace among others examples of the genera Zeptoena, Spirifera, 

 Terebratula, and Nucula. The smaller Mollusca prevail toward the top of 

 the bed, diminishing in number downwards, and giving place at bottom to 

 the larger, such as Ammonites, and occasionally a Belemnite. "With 

 regard to its extent, I have detected it at three points on the hUl, bearing 

 from each other in angular directions ; a fact which firmly convinces me of 

 its persiotency over nearly the whole entablature of its summit. On the 

 top the Leptcena bed is bounded by a film or crust of the before-mentioned 

 orange-coloured substance, about one-eighth of an inch in thickness ; thus 

 marking a convenient and distinct boundary line. Above this line comes 

 a layer of clay, which does not differ materially from the Marly clay above 

 the Fish Bed. The layer, Tfo. 4, is rather Marly in the upper part, owing 

 to the great proportion of Ume it contains. Below, the clay shales assume 

 more of an unctuous nature, and do not divide readUy into laminae, as do 

 those in the other quarry ; when separated, the surfaces often present 

 a puckered and mammiUated appearance. The qiiasi Fish Bed has now to 

 be noticed. I qualify it with this prefix, since the organic contents of it 

 differ neither in kind nor degree from the clay shales lying under and over. 

 If the appellation Fish Bed be used, it must stretch with some elasticity 

 over eight feet or more. This is probably the case with aU three of the 

 so-called Lias Fish Beds ; those of "Wainlode and "Westbury will recur to 

 the minds of geologists as analogous instances. The Fish Bed, then, 

 thus qualified, applies to a stratum taking an irregular course, sometimes 

 tending towards the top soU, but mostly pursuing a midway direction 

 through the eight feet of clay and shale (Nos. 2 and 4). It is composed 

 of a yellowish argUlaceous Limestone, of concretionary nature, opening to 

 the hammer with a foetid odour, whence the term Stink-stein of the 

 Germans; towards the centre it is siliceous, exceedingly hard, and of 



