KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 41. N:0 4. 15 



Shell as in the foUowing species var. intermedia Knipowitsch 1901. 



+ + . Laterals of the radula with smooth margin. Apex and the superior 



lobe of the aperture transversely truncated. Head-lobe < the mantle, 



white with light döts. L. 11 mm, shell Ph. fragilis G. O. Särs 1878. 



II. Spiral striie cousisting of confluent inipresscil imiictui^es; outer lip unifoniily avcuated and pro- 

 minent above the apex. L. 2 nini, shell l'h. ciiigulata (t. O. Särs 1878. 

 B. Radula with a rudimentary unciniis on each side, 1.1.0.1.1; shell exten- 

 ded in length, with catenarian spiral strise. 



1. Aperture-margin not extended beyond the apex, rounded or forming nearly 

 a right angie below. Onter lip not compressed at the top but strongly 

 sinuous; the margin serrated below and at the top. Animal yellowish or 

 greenish white, sometimes with black spöts. L. 15 mm, animal; 8 mm, 

 shell Ph. scabra (Muller 1776). 



ri. I figs. (] -8: Pl. III fig. 2. 



Outer lij) compressed (slightly sinuous) at the top; the margin less ser- 

 rated or smooth, rounded below var. Lo veni Malm 1853.'^ 



Pl. I fig. 9. 



2. Aperture margin extended beyond the apex, uniformly rounded in front 

 and serrated. Animal yellowish white, the parapodia with reddish brown 

 spöts. L. 10 mm, animal; 4 mm, shell Ph. catena (Montagu 1803). 



il. Stomach-plates rudimentary, cartilaginous ; radula with 2 uncini on each side, 

 2.1.0.1.2; spiral sculpture consisting of oval rings. 



a. Outer lip not extended above the apex; aperture i'egularly oval, rounded be- 

 low. Animal light yellow with reddish brown döts; head-lobe oval. L.. 5 

 mm, animal; 2 mm, shell Ph. punctata (Clark 1828). 



11. Outer lip extended above the apex, angled and projecting outwards at the top; aperture nearl\- ijna- 

 di'angular. truncated below; Avliorls with a keel at the sutiire. L. 3 nnn, shell 



Ph. auyulata Jeffrrys 18(i7. 



ITT. Stomach-plates absent; radula with uncini, which are 

 A. strong, hamate. 



1. on each side 1 (radula 1.1. t). 1.1); shell smooth. elongated; outer lip acute-angled above, 

 as high as the apex. Head-lobe oval. L. about 4 inm, animal; 1,S mm, shell 



Ph. sinuata Stimpson 1850 = nitida .Jeffreys 1887. 



2. on each side 2 (radula 2.1.0.1.2); shell with catenarian spiral striae. 

 a. Spire not prominent. 



-I-. Shell rhomboidal, slightly contracted below the apex, which is narrow, 

 of the same breadth as the superior lobe of the aperture. Head-lobe 

 cut ovit behind. L. 16 mm, animal; 7 mm, shell 



Ph. quadrata (Wood 1839) = scutulum Loven 1846. 

 + -I- . Shell oval ; apex broadly rounded. Head-lobe slightly incised behind 

 in the middle. L. 5 mm, animal (contracted); 3,5 mm, shell 



Ph. polaris Aurivillius 1887. 



^ Tliis variety. hdwcvei', passes över into the type throuKh a series of intermediate forms (see Pl. I 

 figs fi— 9). 



