Fam. 3, Plate 39. 



HER1VLEA BIFIDA, Montagu, sp. 



H. gracillima, postice attenuata, pellucida, alba, duobus lineis rubris signata; branchiis ovato- 

 linearibus, insequalibus, roseo-tinctis, pellucidis, vase centrali rubro, ramoso ; seriebus indistinctis utroque 

 dorsi latere digestis ; tentaculis involutis, truncatis ; lateribus anterioribus pedis rotundatis. 



Doris bifida, Mont., in Linn. Trans., v. 12, p. 198, pi. 14, f. 3. 



Tritonia bifida, Flem., Brit. Anim., p. 284. 



Thomp., in Ann. Nat. Hist., v. 7, p. 480. 



Hermeea bifida, Loven, in OfV. Kon. Veten. Akad., 1844, p. 50. Index Moll. Scand., p. 7. 



Hab. Among sea-weeds and zoophytes near low-water mark, and in shallow water. Devonshire, 

 Montagu. Belfast Bay, Mr. Getty and Mr. Hyndman. Black Rock, Leith, Rev. D. Landsborough, junr. 



Body nearly an inch in length when extended, but capable of great contraction, linear, 

 very slender, pellucid, and of a pale yellowish colour. Tentacles rather short, truncated, and 

 longitudinally folded or involuted ; open down the exterior side, and produced above into two 

 unequal points ; the anterior one short, the posterior long, and generally curved a little 

 forwards. These points, and the opening down the side, give the tentacles the appearance of 

 being bifid. The tentacles are red before and behind, and yellowish-green at the sides. 

 Head small, a little arched in front, and slightly produced at the sides. The upper part of 

 the head, and between the tentacles, is lake-red, behind these there is a pale area in which 

 the eyes are placed, succeeded by a central red blotch on the back ; and two dark red lines, 

 formed by the gastric vessels, run down the sides of the back nearly to the tail. These are 

 slightly branched ; the principal branches running into the papillae. The ridge of the back 

 and the sides below the papillae are minutely freckled with lake-red. Branchia numerous 

 and very unequal in size, some of them being long, and others extremely short. They are 

 linear-ovate, pointed at the top, and a little tuberculated on the sides towards the upper part ; 

 but in this they are very irregular, the outline varying much according as they are expanded 

 or contracted. They are very transparent, and nearly colourless, having only a tinge of rose- 

 colour over the surface. The central vessel, which is lake-red, is very slender, and extends 

 the whole length of the papilla, sending off verticellated branches, which are subdivided 

 at their extremities, giving the papillae an elegant dendritic appearance. The papillae nearly 

 meet on the back a short way behind the tentacles, and are set down the sides in ten or 

 twelve indistinct transverse rows, containing two or three papillae each. Foot linear, very 

 narrow, nearly colourless below, and freckled with red at the sides ; between it and the head 

 there is a streak of grass-green. In front it is a little expanded, and slightly belobed. The 

 tail is very slender and extensile, being occasionally produced a great way beyond the 



