76 JOURNAL AND PROCEEDINGS 



Iron band" (Clinton) close to and above the "Upper Reservoir," we 

 find "a Lingula" which Sir Wm. Dawson thinks may be a variety of 

 " Lingula Oblata." It differs from the latter, chiefly, in being 

 abruptly bent near the extremity of the posterior margin. At first I 

 imagined it was distorted by pressure, but I now think this view 

 erroneous, as the peculiarity has been remarked in several specimens 

 from different beds. Another small Lingula from the same horizon 

 and locality, displays " brown spots on a white surface," the beak 

 being rather like that of " Lingula Cuneata " (Conrad) It may be 

 asked, have we reason to suppose that colored fossils may yet be 

 discovered in older rocks than our local ones here. I think they 

 will be found in the " Cambro-Silurians," for in a " Hudson River" 

 drift pebble at Burlington Beach I noticed a fragment of a crimson 

 Lingula, while several years ago another fragment was obtained at 

 Anticosti corresponding in color. I recollect extracting from a rock 

 on the north shore of that island "a Pleurotomaria," retaining its na- 

 creous lustre precisely like a fragment of an Ammonite (Am. 

 biplex) in my possession, which was obtained from the upper Oolite 

 Kimmeridge clay, England. I know the belief is usually accepted 

 that Tropical shells owe (as a general rule) their greater brilliancy to 

 the sun's influence in the regions they inhabit — " that the mantle of 

 the shell possesses the power of decomposing light and of secreting 

 or appropriating color." This may be true enough, however, in 

 the case of " Ianthina fragilis " (the Violet Sea-snail) many natural- 

 ists, who have closely studied the subject, stating that the shell's color 

 is derived from " the blue Velella " it feeds upon. If this fact was 

 clearly established it would be but natural to suppose that it is not 

 the only Mollusc which is indebted to the plants or minute 

 creatures which they live upon for at least a portion of their bril- 

 liant hues. Dealers, for instance, can discriminate between " the 

 natives" (green oysters feeding on " Conferva? " in artificial parks) 

 and the same bivalves from the natural oyster-beds, by the shells 

 themselves. With reference to the colored shells of the later 

 Palaeozoic Rocks, I find at page 410 Boston Edition " Ly ell's Ele- 

 mentary Geology " the following remarks under the head " Moun- 

 tain Limestone " : — 



" The mere fact that shells of such high antiquity should have 

 " preserved the pattern of their coloring is striking and unexpected ; 

 "but Professor Forbes has deduced from it important geological 



