1881. ] Recent Literature. 727 
are wound in a long helix round the swim-bladder. The deter- 
mination of the structure of the jaws and their functions in the 
peculiar genus Exog/ossum was first made in Professor Cope’s paper 
on the Cyprinide of Pennsylvania, published in 1861. Professor 
Cope thinks that additional species will be found in the Ohio 
tributaries, which now includes half the fresh water fish fauna of 
the State. The eastern limit of distribution of a number of 
species is pointed out, and the southern limit of others. 
printer. 
We hope the commissioners will persevere in their work until 
all our fresh waters furnish a permanent supply of good fish food 
for our rapidly increasing population. 
STUDIES FROM THE BIOLOGICAL LABORATORY OF JOHNS HopkKINS 
Universrry}—While this part contains valuable physiological 
papers by the editor, Prof. Martin, and by Drs. Councilman, 
Hartwell, and Sewall, we propose to notice here the purely zoologi- 
cal memoirs, which are of a high order of merit. In Dr. S. F. 
Clarke’s paper on the early development of the Wolffian body in 
the common salamander (Amblystoma punctatum), which is illu- 
Strated by three well drawn plates, the author states that this 
body arises from the outer layer of the mesoderm as a solid rod 
of cells, and is at first largest anteriorly; a split then occurs in 
the larger portion which begins at the posterior end of the smaller 
part and travels anteriorly, and at this time a lumen has appeare 
in the anterior end of the blastema ; finally, the split reaches the 
anterior end thus dividing that portion into two ducts; the lumen 
is extending itself backward, a small rod of cells has been formed 
low the anterior end of the ventral duct, the dorsal and ventral 
ducts are united at one point, and a second opening into the body- 
cavity from the dorsal duct has been made. This method of de- 
velopment seems to be quite different from that in any allied 
forms in which the development has been worked out, and, adds 
r. Clarke, it is most like that of the Elasmobranchs. 
A paper by Dr. C. Sihler, on the formation of dentine and of 
Osseous tissue is followed by one by Prof. W. K. Brooks and E. 
B. Wilson on the first zoéa of Porcellana, illustrated with two 
. Fohns Hopkins University, Baltimore. Studies from the Biological Laboratory. 
Editor, H. NEWELL MarTIN; Associate Editor, W. K. Brooxs. Vol. u, No, f. 
Published by N. Murray, Johns Hopkins University. June, 1881. 8vo, pp. 134- 
Subscription price for the vol., $5.00, : 
1 
