NUDIBRANCHIATE GASTEROPODA. 27 



This species, which, like the typical one, is distributed over the northern parts of both the 

 Atlantic and the Pacific ocean, is already sufficiently marked by its large and broad frontal veil, 

 and by its simply fingered sheaths of the r hi nop h ores (and the want of appendages at the 

 outside of these). Constant differences in the inner structure between this and the typical species 

 have hardly been pointed out. 



On the 5 th of August 1895 a single specimen was fished on Dyrafiord (on the west coast of 

 Iceland), which was killed by means of anhydrous acetic acid, and preserved in 7o / alcohol. 



The well preserved specimen that was scarcely contracted to any appreciable degree, was 4 cm 

 long, by a height of the body of r2 cm , and a breadth likewise of r2 cm ; the breadth of the frontal veil 

 from one point to the other 2'$ c "\ the breadth of the head proper under the veil io mm ; the height of 

 the sheath of the rhinophores with their snips 6 mm , the height of the branchial tufts up to y mm ; the length 

 of the foot almost J5 cm by a breadth of up to n cm ; the breadth of the foot-brim 3-5"™, the length of 

 the tail io mmI ). - - The colour was whitish; but a few of the fingers of the frontal veil, the club of 

 the rhinophores, the stem of some branchial tufts, and the genital papilla still showed remnants of 

 an earlier red colour 2 ). 



The form was as before described by me. The head proper, which was strongly convex, 

 somewhat half-mooushaped, showed below the vertical mouth-slit, while the frontal margin had a 

 series of sessile or quite shortstalked papulae (fig. 1). Behind the head the enormous (from before back- 

 wards almost 5 mm broad) frontal veil was seen projecting strongly on the sides with its cleft ends; it 

 bears a series of tentacle-like, unequally large appendages of a length of up to 4— 5 mm , and set with 

 small knots or short branches (fig. 1). Also between the frontal veil and the frontal margin of the head 

 small papula? are seen here and there. The sheath of the rhinophores as usually high (fig. 27), at the 

 top running into 4 — 5 unequally large, fingershaped continuations; the club as usual; no appendage 

 at the base of the sheath. On the right margin of the back were seen four branchial tufts, and on 

 the left margin six more irregular ones; the foremost were bipartite, the stems at the base separated 

 or nearly united, and outside of these still a satellite like a branchial tuft was seen, in a few instances 

 coalesced with the branchial tuft proper; this satellite was wanting in the hindmost branchial tufts. 

 On the tail were seen medianly three unpaired gill-like appendages, but only the foremost one showed 

 any trace of leaves (fig. 2). Closely in front of the right second branchial tuft the anal papilla and 

 the renal pore were seen. The back was quite smooth, without any papulae or small appendages. 

 The genital papilla as usual strong, with conically projecting praeputial papilla in front, and behind 

 this a bent, strong fold covering the vulva. 



The intestines were nowhere distinctlj- seen from without, only on the sides the}' shone through 

 with a grayish tint. 



The visceral cavity reached to the base of the tail. 



The central nervous system was milk-white. In the cerebro-pleural ganglia the two 



') Harrington, in the biological section of New York Acad, of sc. (9th of Novbr. 1896), pointed out that the large, 

 pale specimens of . Dendroiiotus> from Puget sound could reach a length of full 25 cm . Comp. Anatom. Anz. XIII., 1S97. p. 95. 



2 ) According to Sars (I.e. p. 315) the living animal is said to be light red (laete rufescens) with numerous scattered 

 white dots. 



