OF THE FIRTH OF FORTH. 63 
very small, but it must be further reduced, because of the 
impossibility of determining with certainty the species re- 
ferred to by many of the older writers, on account of the 
confusion which has existed between some of the allied forms, 
and the tangled mass of synonymy in which other species 
have become hopelessly involved. Accordingly, with the 
exception of Alder’s two species of Parascidia from the Isle 
of May, and of Pelonaia corrugata (F. and G.), which was 
first discovered by Professor Goodsir, in deep water, off 
Anstruther, in 1841, and which was dredged near the Bass 
Rock in 24 fathoms by the German North Sea Expedition of 
1872, we have given in the following list only those species 
which we have ourselves collected in the Firth of Forth. 
ASCIDLH SIMPLICES. 
MOLGULIDA. 
Molgula citrina (Alder and Hancock). 
This little species was first described by 
Alder in his “ Catalogue of the Marine 
Mollusca of Northumberland and Dur- 
ham,” * and, so far as we are aware, it has 
not been mentioned since. 
We have come upon it several times dur- 
ing the last two years, adhering to the 
under surfaces of large stones, about low 
water mark, between the Chain Pier and 
Granton Harbour. 
Bugyra glutinans (Moller). 
This species has a most extensive syno- 
nymy, and is usually known as Molgula 
(or Hugyra) arenosa (Ald. and Han.). 
Lately, however, Traustedt + has declared 
that it is identical with the species de- 
scribed in 1842 by Moller? as Cynthia 
glutinans. 
* Trans. Tyneside Nat. Field Club, vol. i., p. 199 (1850). 
+ Oversigt o. d. f. Danmark, etc., Asc. Simp. (Vid. Medd. nat. For. 
Kbhvn, 1879-80), 
t Index. Moll. Groenl., 1842, p. 21. 
