EGGS OF FISHES 185 
Bolau.* The egg case of Callorhynchus (Fig. 191) is 
essentially shark-like; it is of spindle-shaped outline, and 
_ its broad, fringing margin gives it an almost seaweed-like 
appearance. .The egg is believed to be deposited in deep 
water. 
The spawning of but one of the three existing Lung- 
fishes has been recorded. Ceratodus, according to Semon, 
has a spawning season extending over several months; it 
deposits its eggs in shallow water, scattering them broad- 
cast. The female fish is attended by several males, and 
the emission of eggs and milt appears to be simultaneous. 
The egg (Fig. 192) lacks a horny capsule, but is amply 
protected by a thick, jelly-like hull. It hatches during the 
second week. 
Eggs of Ganoids are shown in Figs. 193, 194. They 
are encased in a jelly-like envelope, especially viscid in the 
case of sturgeon. When deposited, they speedily adhere 
_ to whatever they touch, and often remain attached until 
the time of hatching. The spawning grounds are in 
shallow water; the fish occur in numbers during a few 
days of May and June, each female attended by several 
males: ova and milt are emitted simultaneously, at short 
intervals. The eggs develop rapidly, hatching in about a 
week. 
The eggs of Teleosts present the utmost variety in 
number, form, membranes, and mode of deposition. In 
some forms (Embiotocids, Blenniids, Cyprinodonts) they 
may even develop within the ovarian tissue, establishing 
there a “placental” circulation. They have been fertilized 
within the fish, the anal fin spine of the male having in 
some cases been metamorphosed into a copulatory organ. 
The eggs of Siluroids (Fig. 195) are generally of large size, 
*V. Ref. p. 241. 
