820 Proceedings of the Royal Irish Academy. 



teristic featui'es of tlie Britisli A. pulcJier, viz. the secondary 

 cephalic fiurows and the reserve stylet in the central stylet 

 apparatus ; neither of these points is mentioned by Biirger, nor 

 is the latter shown in his large anatomical figure (1895, pi. ix., 

 fig- 8). 



Pive specimens, ranging in length from 2 to 7 cm., were 

 dredged in A^alencia Harbour. They agreed with those found at 

 Plymouth. 



Distrihiition. — Plymouth Sound (Eiches) ; Falmouth Har- 

 bour ; Isle of Man (?)i (W. I. B.). 



Family— TETRASTEMMID^. 

 Genus — Teteastemma. 



Since dealing with the Port Eiin ISTemertines, in 1895, all 

 my experience has tended towards fui'ther confirmation of the 

 view of expressed by Eiches (1893) regarding the unsatisfactory 

 natui'e of the specific characters in the genus Tetrastemma ; 

 especially in T. candidiim and its allies. 



I am more than ever convinced that the presence, shape, and 

 exact position of patches of pigment on the head are featui'es 

 of very doubtful value in the discrimination of species. It was 

 hoped that a complete revision of the genus on more satisfactory 

 lines would appear in the iS'aples Monograph. Unfortunately 

 Burger, in his systematic account, has done little more than 

 add a number of new species ; for the most part very inade- 

 quately characterized, and based, in some cases, on single 

 specimens. 



^ Since writing my Report on Port Erin Nemertines (1895) I have had opportuni- 

 ties of examining small examples of A. dissimulans. They have the same semi- 

 transparent milk-white appearance as the adults, and they are stouter than specimens 

 of the Port Erin Ampldporiis of the same length. The latter are of a brownish 

 yellow or dull orange colour, due largely to pigment in the skin, and entirely lack 

 the opaque white specks (gland cells) so plentifully scattered all over the surface 

 of A. dissimulans. I am now disposed to consider the Port Erin animal as worthy 

 specific rank. The two are found in quite distinct habitats: — A. dissimulans 

 always, so far as I know, among muddy stones and shells in enclosed harbours ; 

 while the Port Erin Amphiporus occurs on clean ground (shells, NuUipores, and 

 gravel) in the open sea. 



