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



15 



Shell as in the following 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 dots. L. 11 mm, shell Ph. fragilis G. O. Sars 1878. 

 I). Spiral striae consisting of confluent impressed punctures; unter lip uniformly arcuated ami pro- 

 minent above the apex. L. 2 mm, shell Ph. cingulata (J-. 0. Saks 1878. 

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

 ded in length, with catenarian spiral stria?. 



1. Aperture-margin not extended be}^ond the apex, rounded or forming nearly 

 a right angle below. Outer 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 spots. L. 15 mm, animal; 8 mm, 

 shell Ph. scabra (Müller 1776). 



PI. I figs. 6 — 8; PI. Ill fig. 2. 



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

 rated or smooth, rounded below var. Loveni Malm 1853. 1 



PI. I fig. 9. 



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

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

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



II. 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 regularly oval, rounded be- 

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

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



I>. Outer lip extended above the apex, angled and projecting outwards at the top; aperture nearly qua- 

 drangular, truncated below: whorls with a keel at the suture. L. 3 mm. shell 



Ph. angulata Jeffreys 1867. 



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

 A. strong, hamate, 



1. on each side 1 (radula I. 1.0. 1.1): shell smooth, elongated; outer lip acute-angled above, 

 as high as the apex. Head-lobe oval. L. about I mm, animal; 1.8 mm. shell 



Ph. sinuata Stimpson 1850 = nitida Jeffkeys 1867. 



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

 a. Spire not prominent. 



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

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

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



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

 + +. 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. 



This variety, however, passes over into the type through a series of intermediate forms (see PI. 1 



