OF THE FIRTH OF FORTH. 67 
Thelepus circinatus (Fab.). 
Firth of Forth, 30 fathoms; Bass Rock, 
24 fathoms (M6b.). 
SABELLID. 
Sabella pavonina (Sav.). 
Very common on the oyster bank, and in 
deeper water; also in sand at. Aberdour 
at very low water. 
SERPULIDA. 
Serpula vermicularis (Linn.). 
Common, off Inchkeith, 5 fathoms, ete. 
(nob.). 
Spirorbis borealis (Davd.). 
Very plentiful on Algze at low water. 
S. lucidus (Mont.). 
On Hydroids, ete., in all parts of the 
estuary. 
PYCNOGONIDA. 
This group has been recently separated from the CRUSTACEA 
and ARACHNIDA, with which it was formerly associated, and 
arranged as an independent class of the ARTHROPODA. 
NYMPHONID/. 
'Nymphon gracile (Leach). 
Not uncommon among stones and weeds 
between tide marks, and we have dredged 
it off May Island, 14 fathoms; Kirkcaldy 
Bay, 6 fathoms ; off Inchkeith, 5 fathoms; 
and in many other parts of the estuary. 
PHOXICHILIDA. 
Pycnogonum litorale (O. F. Mill). 
Common between tide marks, but also 
found in deep water. We have dredged 
it in 18 fathoms. We found specimens 
near Inchcolm, at the end of April of this 
year, having large masses of ova attached 
to them. 
