KUNGL. SV. VET. AKADEMIENS HANdIINGAR. BAND 41. N:0 4. H 



divergent, with a furrow on the under side. Body gelatinous, yellow or reddish, 

 with whitish spöts. Shell internal, oval, flexible, with the spire över the side ; whorls 

 2, very minute. L. about 30 mm, animal; 15 mm, shell 



P. plumula (MoNTAGU 1803) = sideralis Loven 1846. 



Fam. Umbraculidae. 



Tylortina Rafinesque 1819. 



Head with a velum, terminating in tentacular lobes. Radula oo . 1 . oo . 



Shell ovate, depressed-conic, obsoletely angulate-radiate, with two incomplete 

 sinistral nuclear whorls at the reciirved apex. Animal oblong, the head withont 

 roötrum, deeply slit in front into lanceolate lobes; rhinophores ear-shaped. Colour 

 of the animal and epidermis of the shell purple. L. 10, t mm, shell. (Pilsbry 1895). 



T. Duebenii Loven 1846. 



The followins' forras, ]ierliaps young specimens of Philiue, may he added to the Tectihranchia. 



Colpodaspis M. Särs 1870. 



Head with a pair of tentacles : foot with expanded anterior lobes. Sliell internal, slolmse-ovate, with the 

 apex twisted, truncated; whorls 3. Radula 2. 1.0.]. 2. 



L. of the shell, 1^3 mm. (Särs); L. of the animal 2,ri mm. (Särs) or 3 Vi mm. (Gakstaxg 1S94). 



('. pusilla M. Saks 1S70. 



Colobocepliiihis M. Särs 1870. 



Head with tentacle-shaped side-lobes; foot dilated in front. Shell external, siihauriforra, very thin. with 

 or without an indistinct epidermis; spire small: whorls 3; eolumella sinuous. Eadula 2.1.0.1.2. 



Shell with transversal costa^. L. 2,7 mm, animal; height of the shell 2 nim, breadth 2^3 mm. 



C. costellatns M. Saes 1S70. 



Fam. Tritoniidae. 



Tritoiiia Cuvier 1802. 



Ventriculus without dentition. 

 I. Velum incised in the middle, with small papillse; radula with numerous laterals 

 (subg. Tritonia). 



A. Back slightly convex, warty; the bigger äppendages (5 — 6 on each side) 

 distinctly pedunculate, flexed inwards, the smaller ones prominent outwards; 

 porus genitalis close by the margin of the back, half way between head 

 and anus. Colour yellowish, brown or purplish ; äppendages light. Laterals of 

 the radula smooth. L. 70—200 mm. 



T. Hombergi Cuvier 1802 = fimbriata (Vahl 1806). 



pi. II fig. 18, pi. ni fig. 4 

 Laterals of the radula with margin-hooks. L. 25 mm. 



var. alba Ålder & Hancock 1855. 



K. Sv. Vet. Akad. Handl. Bd 41. N:o i. 3 



