Dr. Johnston on the British Nereides, 229 



cies in water, moving forwards principally by the oared leaf- 

 lets that extend from the sides ; but on dry ground its move- 

 ment is slow, and the leaflets are kept applied to the sides 

 and brought somewhat under the body. When kept in a 

 vessel of sea- water, deprived of food, the green colour becomes 

 less intense, and allows us to trace a darker intestine down 

 the centre of the body. When specimens are put into spirits 

 they give out a copious green liquor and tinge the spirit 

 deeply. Immersed in fresh water the worm is evidently pained, 

 but is not killed so instantaneously as some other marine 

 worms are, and in dying does not separate and break in pieces. 

 I have not hesitated to refer this species to the Phy. clavi- 

 gera of Audouin and Edwards, although some slight differ- 

 ences may be traced in our figures ; for some experience has 

 brought me to believe that, in comparing figures which have 

 been made under the magnifier, we are not to look for an ex- 

 act resemblance between them. I have seen figures drawn 

 by the same individual and from the same objects at some- 

 what distant periods, but with every desire to be accurate, 

 between which the discrepancy was greater than could have 

 been at first imagined. So also I have not expressed any 

 doubt of their species being identical with the Nereis vi- 

 ridis of Otho Fabricius, for the only distinction pointed out 

 by Audouin and Edwards between them is the absence of the 

 odd antenna in the latter, and this is only inferred to be the 

 case from the silence of the Greenland naturalist. But it is 

 no imputation on the acknowledged accuracy of Fabricius to 

 believe that this organ may have escaped his notice ; for, even 

 afler having been made aware of its existence, I have some- 

 times found that it was no easy matter to bring it into view 

 and make it perceptible to others. 



Plate VI. fig. 11. P. viridis, of the natural size. Fig. 12. The head and 

 anterior segments, magnified. Fig. 13. The head and proboscis extruded. 

 Fig. 14. The middle segments seen from below. Fig. 15. The caudal ex- 

 tremity. 



3. PsAMATHE, Johnston, 

 Char. Body scolopendriform : head small : eyes four, in 

 pairs : antenncB four, short, unequal, biarticulate : proboscis 

 thick and cylindrical, its aperture encircled with a series of 



