On the Development of the Angler (Lophius piscatorius, L.) 
By €) J. Connoriy, “Pap: 
St. Francis Xavier’s College, Antigonish, N.S. 
S S 
INTRODUCTION. 
During the summer of 1918 the writer made a study of the distribution, etc., 
of the Angler in Canadian waters and gave a general account of the life-history 
of this fish in Bulletin No. 3, issued by the Biological Board of Canada. The 
detailed results of observations made during that season are contained in the 
following paper. 
While carrying on another investigation at the Biological Station, St. Andrews, 
N.B., during the summer months of 1919 and 1921, additional observations were 
made on the early stages in the development of the Angler, and these are also 
included in this paper. 
I wish here to cordially thank Dr. A. G. Huntsman, Curator of the Biological 
Station, for his kind assistance and many valuable suggestions while making 
this investigation. 
OvA OF THE ANGLER. 
The period of spawning of the Angler, Lophius piscatorius, in Canadian 
waters extends from about June to August. The eggs are embedded as a single 
layer in a mucous band about thirty or forty feet in length, and this gelatinous 
mass floats near the surface of the water. Fulton (1898, p. 118) has shown that 
the mucoid substance is secreted by a specially modified epithelium. He has 
further described the development of the ovarian eggs of Lophius from the 
earliest stages to their maturation and has shown that the increase in volume of 
the eggs during maturation is due to the imbibition of a watery fluid. The 
specific gravity of the mature ovum, according to Milroy, is 1.034, while the 
specific gravity of the mucous band, together with its mature ova, is 1.005. 
The floating properties of the egg are due to the mucous substance. They are 
pyriform when embedded in the mucous substance, but when free they assume 
a more spherical form, though they still retain the flattened surfaces due to the 
pressure of adjacent eggs. There are many small oil globules in the immature 
egg, which fuse in the ripe egg to form one large oil globule. 
DEVELOPMENT. 
Agassiz described the young embryo just before hatching and also the early 
larval stages. Prince described and figured embryos at the stage just before 
hatching and also the early larval and post-larval stages for the European form, 
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