Mr. Thompson on the Mollusca of Ireland. 91 



^Length 10 lines, mouth "sub-inferior terminal;" frontal appen- 

 dages 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, cla- 

 vate, 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 ^^as placed for examination 

 was regular and graceful. It was dredged in Strangford 

 lough, adhering to a Laminaria, by Mr. Hyndman and my- 

 self, in January, 1835. The description and figure were taken 

 from the living animal. 



Of the genus Euplocamus I know^ but five species, three of 

 which, described by Philippif, have been found in the Me- 

 diterranean alone ; these differ so much from the northern 

 species as to render comparison unnecessary. The E.plumosus 

 in general appearance much resembles the E. clavigera of 

 Muller, but differs from it in having only 3 instead of 4 

 branchial filaments, and in these being plumose — in this cha- 

 racter too, it differs from the E. pulcherX of Dr. Johnston, 

 although the number of these filaments is the same in both; 

 besides, its body and lateral appendages are more elongated ; 

 altogether it is a much more graceful animal than the last 

 mentioned. 



♦ Mr. Forbes suggests that these may possibly be suctorial. 



t E.croceus, Phil. Enum. Moll. Siciliae, p. 103. tab. 7. fig. 1. E.fron- 

 dostts and E. cirriger. Ann. Nat. Hist. vol. iv. pp. 88 and 89. pi. iii. fig. 

 1 and 2. — translated from Wiegmann's Archiv. 



X Dr. Johnston first described this species under the name of Tergipes 

 pulcher, and subsequently constituted a new genus, Triopa, for its reception. 

 Ann. Nat. Hist. i. 124. He was unaware at the time that the same jiulicioua 

 view had previously been taken by Philippi, who founded his genus Euplo- 

 camus on an allied species. This latter name, in right of priority, must be 

 retained. Mr. Forbes has taken the E. pulcher at the Isle of Man and at 

 Shetland ; and joining him, as I do, in the opinion that it is distinct from 

 E. clavigera, I have ventured to restore the original specific name. The 

 genus Triopa will still rank under its banner the anomalous 2'. nothu« of 

 Dr. Johnston. 



H 2 



