256 
shape of which and the consequent increase in surface 
caused the primary ridges to diverge on either side, while 
secondary ridges, looped and otherwise irregular, covered 
the extra surface thus formed. 
III. In our modern walking forms the hypertrophy of the epi- 
dermis has obliterated the markings (are there indications 
of these in the embryo?). 
IV. The arboreal life of Primates has allowed them to keep the 
primitive epidermic markings, and as such they have des- 
cended to Man, indicating the position of the former pads. 
The above, in its use of mechanical causes, sounds very like 
LAMARCK, but, as with all similar theories, it may be equally well 
stated in the language of natural selection. It is not my intention 
to declare my preference for either school of evolution upon such 
purely theoretical grounds as the above. 
Smith College, Northampton, Mass., 
Jan. 4th 1897. 
(Eingegangen am 22. Jan.) 
Nachdruck verboten. 
On the Structure of the Sensory Organs 
of the Lateral Line of Ameiurus nebulosus LE SUEUR !). 
By Frepertc 8. Bunker, M.D. 
The canal of the lateral] line in fishes was observed and described 
with more or less accuracy by many of the earlier anatomists from 
Steno (1664) and Lorenzini (1678) down to the middle of the pre- 
sent century. But it was not until 1850 that it was clearly shown 
that certain sensory organs were distributed along the floor of this 
canal, and that the chief function of the canal was to protect these 
organs and not to secrete mucus, as had heretofore been supposed. 
At this time Franz Leypia (50, 50a) discovered these sense organs 
in Teleostei and described their general topography in some detail; 
and in a long series of subsequent researches extending down to 1895 
1) Contributions from the Zoölogical Laboratory of the Museum of 
Comparative Zoölogy at Harvard College, under the Direction of E. L. Marg, 
No, LXXVII. 
