178 
The Irish Naturalist. August -September, 
was found to vary from i8 to 24, and the denticles in the 
widest tooth of each from 40 to 47. In the largest, and 
presumably the oldest specimen, many of the denticles 
towards the centre of the widest teeth were distinctly 
bidentate and occasionally tridentatc. 
Aeolidiella glauca (Aid. and Hanc). 
Eolis glauca. 
Rare. One specimen trawled in 14-15 f. 3 miles east 
of Kingstown, May, 1907 : Farran, '09. Twice dredged in 
14!'. off Church Island, Skerries in July, 1913, one specimen 
in each haul, both 22 mm. long : N .C. 
The radula in these specimens agreed well in its general 
form with Alder and Hancock's figure ; but the denticles in 
the majority of the teeth were more numerous, ranging 
from 35 to 46 in each half of the double arch. The teeth 
numbered 19 in one specimen and 21 in the other. In 
captivity the last-named specimen spawned while floating 
foot upwards on the water surface. The ribbon was -75 
mm. wide and 135 mm. in length when opened out, a rough 
calculation giving for the coil a total of 11,000 eggs. 
Ae. Alderi (Cocks). 
Eolis Alderi. 
Rare. A single specimen 30 mm. in length, found under a 
stone at low tide, Dalkey Island, May 16, 1913 : Colgan, '13A. 
Another, 20 mm. long, taken here in April, 1914 : N .C. 
This species is very similar to its congener Ae. glauca, 
and doubts as to their distinctness have been expressed by 
more than one authority. The best discriminative character 
is found in the radula, not so much in the form of that 
organ as in its numerical relations. ^hi\e Ac. glauca has 
about 20 teeth with from 33 to 46 denticles in each half of 
the double arch, Ae. Alderi has usually but 15 teeth, with 
from 23 to 25 denticles. These differences might very well 
arise from differences of age and development in individuals 
of one and the same species. Yet since the specimens of 
the supposed two species of Aeolidiella here recorded ap- 
peared to have reached about the same stage of development, 
