276 
MOLLUSCA. 
Length 10 lines ; mouth “sub-inferior, terminal j” frontal appendages 6, 
the two central very small; 3 beautifully plumose branchial filaments, 
situated at about two-thirds the length of the body from the head ; mantle 
separated from the disk by a deep channel; edge of cloak thin and 
waved ; no eyes apparent ; lateral appendages 9 on each side, terminated 
by disks. Colour , body white, tail orange, clavate, tips of the processes 
surrounding the body orange, as are those of the frontal appendages and 
tentacula ; branchial filaments orange ; on the back are a number of 
papillae of this colour, as is likewise a line of spots along each side between 
the cloak and foot. 
The gliding motion of this beautiful species along the bottom of the 
vessel in which it was placed for examination was regular and graceful. 
It was dredged in Strangford Lough, adhering to a Laminaria, by Mr. 
Hyndman and myself, in January, 1835. Lahinch, Co. Clare. 
Genus Tritonia, Cuvier. 
T. Hombergi , Cuv., Johnst. Ann. Nat. Hist., vol. i. p. 114, pi. 3, figs. 
1 and 2. 
A specimen about 4 inches in length, with the examination of which I 
have been favoured by Dr. Ball, was found, some years ago, with oysters, 
at Howth, County Dublin. 
T. plebeia, Johnst. 
A specimen was taken by dredging in Cork Harbour, August, 1843. — 
Dr. Ball and Professor Forbes. 
T. lactea, mihi. 
T. of a milk-white colour, with 6 large branchial appendages on each 
side, bifid and ramosely pinnate ; mantle terminating anteriorly in 4 
arborescent processes. 
Length of specimen (from spirits) 8 lines ; sheaths of the tentacula 
deeply fimbriated. Colour milk-white ; but with the aid of a lens a few 
very minute scarlet dots are seen scattered over parts of the body and the 
branchial appendages. 
The specimen occurred to me when dredging at the entrance of Strang- 
ford Lough, in the month of October, in company with Mr. Hyndman. 
T. arborescens, Cuv. 
Several specimens of a small size were taken by Mr. Alder and Dr. 
Farran at Malahide. Tritonia lactea, Ann. Nat. Hist., vol. v. p. 88, pi. 
2, f. 3, is considered by Mr. Alder a variety of T. arborescens. 
Genus Melibcea. 
M. fragilis, Forbes. 
Three examples of this species were taken on Antennularia antennina , 
dredged in Clew Bay (Co. Mayo) by Dr. Ball, Prof. Forbes, and Mr. 
Hyndman. 
M. coronata, Johnst. 
Obtained at Glandore Bay, County Cork, in August, 1842, by Prof. 
Allman, and subsequently in Dublin Bay by Mr. Alder, who is now of 
opinion that the Melib . ornata, Ann. Nat. Hist., vol. ix. p. 33, is a variety 
of M. coronata. 
In Sept., 1851, this species was dredged in 35 fathoms, off the Copeland 
Islands, by Mr. Hyndman. Its spawn was got at the same time, adhering 
to Sertularia abietina. 
