B. G. Wilder—Anterior brain-mass with Sharks and Skates. 108 
ay to partially isolate certain of the conditions which con- 
trol the rapidity of erosive action, by viewing their influence 
where that influence is at a maximum. 
Art. XL—WNote on the development and homologies of the an- 
=a brain-mass with Sharks and Skates ;* by Prof. Burt G. 
ILDER. 
In the paper to which I have just referredt+ are some state- 
ments, partly original and partly based upon the authority of 
others, which, after a comparison of the preparations before 
yout I now believe to require modification. 
The structure of the so-called lobe and crus.—Accepting the 
* Part of a lecture on the brains of Plagiostomes (one of a course upon the 
brains of the fish-like Vertebrates, to the special students of Natural History at 
Corneli University) delivered May 23d, 1876. 
i Ganoids, 
+ Notes on the ia, Lepidosteus, Acipenser and Polyodon. 
I. On the respiratory actions of Amia and Lepidosteus. II. On the transforma- 
tions of the tail the transformation of the pectoral fins of 
Lepidosteus. IV. On ia, Lepidosteus, A 
Proc. Am. Assoc. Adv. Sci., 1875, 151-194; 3 plates. 
$ These compri dissected, of the following 
Mustelus levis, { foetal, and adult; Zy- 
young, ; “ ; M 
gna, foetal, and adult; Carcharias obscurus (three examples); Triakis ; 
Pontes Americans (ree exaples) Retan: Myliobatis bispinosus ; Tor- 
