170 
The hish Naturalist. August-September, 
times off Dalkey and Howth Head in from 7 to 14 f., 1907- 
13, a total of 20 mature and 2 juvenile specimens : iV.C. 
On the 2nd July, 1908, this species was observed to have 
made a remarkable invasion of the tidal waters between 
Shennicks Island and the Skerries mainland. No less than 
300 individuals of large size, ranging from 5 to 7 inches 
while in motion, were counted at low water crawling over 
the sands or about the base of Chorda filum in water a few 
inches deep. By the 28th of the same month only 50 
specimens could be found here, the majority having probably 
migrated to deeper water. Although no trace of the species 
could be found here in July, 1910, or August, 1911, it re- 
appeared in abundance in July, 1913, when 141 specimens 
were seen, as many as 70 within a space of 50 yards. 
The juvenile specimens, each 5 mm. long, dredged off 
Dalkey in August, 191 1, were a vivid carmine in colour, 
the black eyes were very conspicuous, the margins of the 
median flaps or wings were bordered with black, and 
sprinkled with opaque white spots, while similar spots 
appeared at the tips of the tentacles and formed vertical 
lines along their sides. This juvenile form is no doubt 
Aplysia nexa of Thompson, and /I. rosea of Rathke. Mature 
Dublin specimens range in colour from blotched citron 
through light brown to almost black. 
In Ireland the spawning season of this species is some- 
times prolonged far into autumn. In 1913 I took a freshly 
laid spawn coil in 10 f. off Bullock so late as the 5th Novem- 
ber, and in 191 1 several fresh coils on the shores of Clew 
Bay on the 23rd September. On the 6th July, 1912, coils 
were found to be frequent on Fucus scrratus in half-tide 
pools at Skerries, a rough computation giving for one large 
coil a total of 30,000 embryos at an average of 5 per egg, 
the embryos in this coil ranging from 3 to 7 per egg. The 
eggs hatched out freely in captivity, producing swarms of 
reddish brown veligers. The spawn is deposited on various 
supports, vegetable and animal. At Skerries I have found 
it on Zostera on Chorda filum, on Fucus serratus, and F. 
vcsiculosus ; at Dalkey I have dredged it twice in from 10 f. 
to 12 f. attached to Hydrallmania jalcata and once wound 
