36 



is from here rather abruptly inclined downwards towards the posterior extremity (see fig. 2). 

 Behind these follows, still along the middle of the conically tapered posterior part of the 

 body, a longitudinal row of 5 6 irregular processes, of which the 2 anterior are longest, and 

 which together form an irregularly incised longitudinal keel along that part. The foot (see 

 fig. 3.)' is very slender, linear, tapering to a point at the posterior extremity, and scarcely 

 more than half as wide as the mantle, but tolerably high, (see fig. 2). It terminates in front 

 abruptly truncated at a considerable distance from the anterior edge of the mantle. There 

 is no trace of any labial tentacles, nor of any evident velum; but the anterior part of the 

 foot is as it were separated from the other part by a slight ventral sinus, and curves itself 

 strongly upward towards the bucal aperture, which is concealed in the angle between this 

 part and the mantle. The amis (cloaque) (fig. 1. b) is situated on the dorsal side immedia- 

 tely behind the incavated part bordered by. the longitudinal keels, and is partially hidden by 

 the long processes which project from the posterior edge of the same. The gills which 

 closely surround the anus are particularly small and rudimentary; so that in the specimens 

 examined it was not possible to determine their number or form. The dorsal tentacles (a. a) 

 which are far distant from each other, and attached near the edge of the mantle, are short 

 conical and transversely lamellated, and can be partially retracted in short sheaths. On the 

 right side of the body in front, under the edge of the mantle, there was remarked a small 

 porus (fig. 2. c) which is the genital aperture. The whole animal, together with its various 

 processes, is of a uniform whitish color with slightly transparent yellowish-red intestines. The 

 mantle is everywhere strengthened with chalk spiculse, which are especially conspicuous at 

 the edge and in the dorsal longitudinal keels, and here usually exhibit a radiating arrangement. 



I have only met with this little peculiar deep-water nudibranch at Lofoten, namely 

 at the fishing-place Guldbrands0erne in 120 fathoms, and at Skraaven in 200 fathoms; in 

 both places on soft clay bottom. It was very slow in its movements, which only consist in 

 a gentle scarcely perceptible gliding forwards, during which the body is scarcely curved, nor 

 notably altered in shape. 



This species may be recognised by the following diagnosis: 



Triopa incisa. M. Sars. 



Corpus breve et obesum, supine valde arcuatum, supra visum subovatum, extremitate 

 antica late rotundata, postica subito multo angustiore et conico-acuminata. Pallium magnum 

 et convexum pede multo (duplo circiter) latius et eum antice longe superans marginibus ex- 

 pansis et laminaribus, postice incisum vel in lobos duos triangulares utrinque prominentes 

 desinens, parte postica 4ta corporis nuda et anguste conica. Crista adest in anteriore parte 

 pallii longitudinalis, sat alta sed brevis, in ramos vero duos leviter divergentes se dividens 

 spatium includentes medianum depressum forma elongato-triangulari postici serie transversa 

 processuum elongato-claviformium 5 marginatum quorum medianus et lateralis longissimus. 

 Series longitudinalis processuum similium sed breviorum utrinque inter cristas divergentes et 



