4 The Irish Naturalist. January, 
Six sections of this till were examined, three in Glenulra 
and three in the Owenbehy, and a large collection of shell- 
fragments was made ; the following species were deter- 
mined from the collection made up in Glenulra : — 
Ostrea edulis, Linn. TelHna balthica, Linn. 
Mytilus, sp. Corbula sp. 
Nuculana (Leda) pernula Glycimeris (Panopea) norvegica, 
O. F. Mliller. Speng. 
Cardium edule, Linn. Mya truncata, Linn. 
Cardium echinatum, Linn. Turritella communis, Risso. 
Cyprina islandica, Linn. Purpura lapillus, Linn. 
Astarte borealis, Chem. Balanus poratus. 
From the collection of shell-fragments made in tht 
Owenbehy, Corbula and Purpura were abesent ; otherwise 
the list was the same as for Glenulra. 
3. The third in the sequence is the brownish Boulder-clay, 
which extends widely over the area examined. In com- 
position it varies from tough Boulder-clay, with rounded 
and striated erratics, to mounds of loose rocky debris, and 
in development it ranges from a few inches in exposed places 
to sections of forty or fifty feet in thickness in favourable 
localities. The erratics in this Boulder-clay include 
sandstones, grits, limestones, granite, and mica-schists, but 
the dominant boulders are sandstone, some fairly rounded, 
but the greater number merely blocks and slabs derived from 
no great distance. In Glenulra and the Owenbehy this 
Boulder-clay rests on the eroded surface of the Till, and 
in these places shell-fragments may be found in it in con- 
siderable abundance. This Boulder-clay was searched for 
shells from Lackan to Glenulra, from Glenglassera to 
Porturlin, and also along the Glen valley for eight miles m 
the direction of Crossmohna without a solitary shell-fragment 
being found, so it may fairly be assumed that the shells 
found in it in Glenulra and the Owenbehy were derived 
from the underlying till during the process of denudation. 
The follov^ing is a list of the species identified from this 
Boulder-clay : — 
Mytilus, sp. Telhna balthica 
Nuculana (Leda) pernula Turritella communis 
Cyprina islandica Balanus, sp. 
