A. FE. Verrili—The Bermuda Islands; Geology. 157 
than I did anywhere. He also gives a somewhat greater percentage 
to the calcareous alge, in certain places, than I have done. He fol- 
lows Mr. A. Agassiz in attributing the fine mud and marl entirely to 
the erosion of the rocks and sands of the shore and reefs, overlook- 
ing the very important part that living animals take in the grinding 
up of the shells, etc., as explained in the preceding pages. He 
apparently overlooked the early studies of Nelson, Moseley, and 
others on this subject, and does not refer to them or to my own 
paper (Notes on the Geology of Bermuda,* 1900), even in his bibliog- 
raphy. In my paper of 1900 there was a fairly good though brief 
discussion of the subject, with figures of the sands from photo- 
graphs. He informs me that it was accidentally overlooked. 
One of the most novel and interesting parts of his paper relates to 
the character of the deposits on the Challenger Bank. The bottom 
was found to be covered with rounded pebbles composed of the 
nullipore, Lithothamnion ungeri, on all sides, and carrying serpule, 
small corals (Madracis), bryozoa, etc. From this he concludes that 
wave-action with force sufficient to roll these masses over (some 
were 6 inches in diameter) extends to the depth of 30 to 40 fathoms, 
which is quite contrary to the current scientific belief. 
To me his conclusion that they are continually turned over by 
wave-action seems unnecessary. Plants of that sort require so little 
light that the diffuse and reflected light enables them to grow on the 
lower shaded sides of rounded pebbles in shallow water, though not 
on the parts resting on the bottom. Fishes with burrowing and 
rooting habits may turn such pebbles over frequently and continually 
while searching for their prey, and so might the larger crabs and 
other crustacea, the Octopus, etc., thus causing them to grow on all 
sides and keeping them free of sediment. 
In enumerating the most important genera of shells (p. 568) he 
places the well known bivalves, Codakia, Cardium, and Gouldia 
among the gastropods. 
The fragments of “red Serpula” that he refers to on pp. 566, 567, 
probably are fragments of one of the Vermetide (Zenagodus (Sili- 
quaria) ruber Schum.). I do not know any species of Serpulide 
with red tubes. (See above, p. 139.) 
* Amer. Journ. Science, ix, pp. 313-340, with cuts in text, 1900. 
Trans. Conn. Acap., Vou. XII. il3| Frpruary, 1906. 
