PLYMOUTH NEMERTEANS. 427 



Geographical distribution : North Atlantic and Mediterranean 

 coasts. 



2. Amphiporus dissimulans, Riches. (Joubin. Les Nemertiens, 

 PI. Ill, Fig. 42, and p. 129, Fig. 16.) 



Locality : Dredged from all grounds in the Sound and near the 

 Mewstone. 



Length 5 cm. The colour is variable, most frequently a very pale 

 pink. Head broadly spathulate, pointed, sharply separated from the 

 body. The eyes are never divided into groups and are very numerous. 

 Cephalic grooves as in Joubin's A. roseus. Tail oar-like. 



I should not be surprised if the anatomy of the specimens described 

 by Eiches and Beaumont under the above-cited names proved them to 

 belong to the same species, in this case A. ladifioreus. 



As far as the internal structure is known every evidence of a differ- 

 ence fails. " The shape of the head and of the tail, the number and 

 arrangement of the eyes, the position of the cephalic grooves, and the 

 difference of habitat, A. ladifioreus being a shallow-water form, and 

 these specimens being never obtained in less than 15 fathoms, are the 

 distinguishing characters," says Piiches. 



As to the difference of habitat I cannot agree with Ptiches. Both 

 A. dissimulans and A. ladifioreus have been recorded in dredgings from 

 the same spot, as Asia Shoal, Queen's Grounds, Millbay Channel; 

 moreover, A. ladifioreus proves not to be a shallow-water form alone, 

 as I got quite a typical specimen from the Mewstone Ledge, at a depth 

 of 10-15 fathoms ; A. dissimulans, on the contrary, has been collected 

 at Drake's Island between tidemarks (I cite from the Invertebrate 

 list). But even if a difference in habitat exists, as Eiches supposes, 

 the distinguishing characters might be due simply to this. Certainly 

 it is remarkable that both species are distributed alike in the neigh- 

 bourhood of Plymouth. If A. dissimulans occurs in the deeper parts 

 of the Sound, A. ladifioreus occupies the shores of the same parts 

 (according to Eiches). On the Mewstone it is the same ; in shallow 

 water A. ladifioreus, from the Mewstone Ledge A. dissimulans. To 

 these spots both species seem to be confined. 



As a distinguishing character the arrangement of the eyes does not 

 hold good either. I met with several specimens of so-called A. dis- 

 simulans, the eyes of which were arranged in two groups as in A. 

 ladifioreus. Other specimens had the ladifioreus habitus, but the eyes 

 formed a continuous series on each side of the head. The characters 

 of habitus and arrangement of eyes proved to be quite insufficient to 

 distinguish between the two species. As to the only remaining 

 character, the position of the cephalic grooves, I can only agree with 



