382 W. A. HEHDMAN. 



nephridia, along with T. gigas/ M. Miill., taken off Trieste, 

 from which it may be distinguished by the proportions and 

 shape of the proboscis, which is much wider compared with 

 the body than in T. gig as, and is not trilobed at the tip. 



The other species which liave been described as being more 

 or less of a green colour are — 



(1) T. Baronii, Greef, from the Canaries; but there the 

 probqscis is relatively much smaller, and, moreover, there are 

 important anatomical differences. T. Baronii has two pairs 

 of anterior nephridia, and a different arrangement of muscles. 



(2) T. Moebii, Greef, from Mauritius, with three pairs of 

 anterior nephridia. 



(3) T. viridis, Verrill, off north-east coast of America, with 

 small (6 mm.) swollen body and long slender proboscis. 



The remaining species of the genus which have been found 

 in the North Atlantic or Mediterranean are T. Neptuni, 

 Gaertner (British), T. Frohmanni, Diesing (Sicily), and T. 

 faex, Selenka (between Scotland and the Faroe Islands). The 

 first of these has two pairs of anterior nephridia ; the last 

 agrees with our species in having only a single pair, but 

 differs totally in the structure of the cloacal nephridia, as well 

 as in colour, shape, and appearance generally ; while T. 

 Frohmanni, from the Mediterranean, is insufficiently known, 

 and maybe the same as T. Neptuni. However that may be, 

 T. Frohmanni cannot be confused with T. Lankesteri ; the 

 short description given by Diesing is sufficient to show that 

 our form differs from his both in colour and shape. As a 

 matter of fact, although several of the above-named species 

 have been referred to as more or less green, none of them, 

 judging from the coloured plates given by Greef and others, 

 are so intensely and completely green as our specimens. T. 

 Lankesteri in its coloration is probably more like Ha- 

 mingia arctica than any other known form. 



1 * Observationes anatomicse de Vermibus quibusdam maritimis, Berlini.' 

 T. gigas was originally found at Trieste, and is still taken there. I believe 

 it lias not been found elsewhere; and, as in the case of T. Lankesteri, only 

 females are known. 



