320 Mr. W. Thompson's Contributions to the Fauna of Ireland, 



IMy PasitJioe, together with the two species of Nymphon and the 

 Irenaus, have been seen by Mr. Goodsir. 



Udonella caligorum, Johnston, Loudon's Mag. Nat. Hist. vol. viii. 

 p. 496. f. 45. 



Numerous parasites of this species were attached to a Caligus on 

 a gray gurnard (TrigJa Guniardus), captured on the coast of Down 

 on the 22nd of June hist by Mr. Hyndman. 



Annelida. 

 fBorlasia alba, Thompson. 



Dec. 18, 1843. — Two worms, apparently of the genus Borlasia 

 (Johnston, Alag. Zool. and Bot. vol. i. p. 536) and of the same spe- 

 cies, were found on the beach a short way northward of Carrickfergus 

 by Mr. Hyndman and myself. They were lurking under stones be- 

 tween tide-marks. The species may be described as new, under the 

 name of Borlasia alba : — of a whitish colour throughout, excepting 

 behind the eyes on each side, where a reddish spot appears ; eyes 

 fourteen ; the first four on each side near the margin of the body dis- 

 posed in a line, and at equal distances from each other ; considerably 

 behind them are three at each side disposed in a triangular manner, 

 the base towards the head of the worm : entire length 

 2 inches when stretched out so that its breadth is 1 line 

 oryVth of an inch. 



The annexed outline shows the position of the 

 eyes. 



1 . Reddish spots. 



Planaria cornuta, Miill. Zool. Dan. vol. i. p. 37. tab. 32. f . 5 — 7; 

 Johnst. Mag. Nat. Hist. vol. v. p. 344, with woodcuts. 



Aug. 26, 1844. — Mr. Hyndman dredging today off Castle Chi- 

 chester, just within the entrance of Belfast bay, and at a depth of 

 from 6 to 10 fathoms, took three specimens on Laminarice. Although 

 the figures of this Planaria in the works cited differ a good deal, I 

 agree with Dr. Johnston in believing them to represent the same 

 species. The Irish specimens as observed at various times were more 

 round in outline than Dr. Johnston's figures, and consequently quite 

 different from those of Midler in that respect. The network of red- 

 dish " vein-like ramifications " on a cream-coloured ground renders 

 this Planaria viewed as a whole very beautiful : the multitude of dot- 

 like black eyes on a rich white ground too looked very elegant from 

 the contrast of the white to the general reddish hue of the animal. Its 

 progress, as Dr. Johnston remarks, " for a worm " is not slow : the 

 tentacula were always reflected backwards so as not to be visible in 

 a profile view. The species has been already so fully described that 

 further observations are unnecessary. One which I left gliding about 

 in sea-water apparently in perfect health, was when I looked at it 

 again after eighteen hours not only dead, but almost wholly decom- 

 posed. 



