Dr James M'Bain 071 the Development of Fish Spaion. 373 
the larva of Notodonta or AmpMpyra, and the rest of the 
body is uniformly cylindrical, the fifth and the sixth seg- 
ments bearing a pair of large eye-like spots, somewhat like 
those of the larva of Chcerocampa. The position, when at 
rest, is most remarkable, the body resting on the three pairs 
of perfect ventral claspers alone, with the anterior segments 
elevated and incurved, after the manner of the Sphinges, 
and some of the Geometrm, while the posterior segments are 
elevated in the air after the fashion of the genus Notodonta. 
The drawings are on their way to London, I believe, to 
be placed in the hands of Mr Moore ; so that their details 
may be expected to be embodied in the forthcoming volumes 
of the Descriptive Catalogue of the Insects in the Museum 
of the East India Company. 
II. Notice of the Development of Fish Spawn from the Firth of Forth. 
By James M'Bain, M.D., R.N. 
On Tuesday the 11th instant, when examining fish spawn 
under the microscope, I observed a free and complete rota- 
tion of the embryo in the ovum, which rotatory movement 
was repeated at short intervals. The spawn had been 
dredged up four days previously in 14 J fathoms water, half 
a mile to the westward of the Isle of May ; and in all the 
ova which had a clear transparent appearance the same rota- 
tory motion was observed. The following day, on making 
similar observations, the embryos were still found alive, 
and rotating freely in the ovum ; and fresh spawn dredged 
up at the same place exhibited similar activity of embryonic 
movement. The spawn in which this vital action was seen 
is said by the fishermen to be the herring spawn ; and to as- 
certain, if possible, to what species it really belongs, I pre- 
served small portions of the spawn in sea-water. On the 
18th instant, I was pleased to see a numerous brood spon- 
taneously extruded from the ova, swimming freely about in 
the vessels in which they had been placed. 
The ova were about aV^h of an inch in diameter, and the 
young fry, when first extruded, measured two to three lines 
in length. A few of the young fish are now, eight days 
