SOME POINTS IN THE ANATOMY OF POLYCH^TA. 253 



brate in having a number of nephridia coalesced to form a 

 continuous longitudinal tube. 



It is surprising to find that, as far as I have been able to 

 discover, no resemblance to the condition seen in Lanice con- 

 chilega occurs in any of its near allies. The only species of 

 the genus Terebella as defined by Malmgren that occurs in the 

 Firth of Forth is Terebella Danielsseni, but of this I have 

 only one specimen, and have not examined its nephridia. Of 

 Amphitrite there are two species in the Forth; Am phi trite 

 cirrata I have not examined anatomically ; in Amphitrite 

 Johnstoni there are a large number (fifteen to seventeen) of 

 nephridia forming long loops projecting dorsalwards into the 

 body cavity in the anterior region ; each has its own internal 

 and external openings, and is isolated and independent. In 

 Terebellides Strcemi there is one pair of large dark- 

 coloured nephridia in the anterior end, and three pairs of small 

 rudimentary ones posterior to this. 



In Pectinaria belgica there are three pairs, all indepen- 

 dent; they are described in the following section. In 

 Melinna cristata there are several pairs all separate. 



Pectinaria belgica, Lamarck (Pallas). 



Mr. Harvey Gibson 1 has by carefully neglecting the distin- 

 guishing differences between this species and Amphitrite 

 auricoma, Muller, attempted to prove that the two forms are 

 identical. He points out that in the original figures of Pallas, 

 of Nereis cylindraria, var. belgica, "the stiff golden comb 

 shows one continuous and uniform series of teeth, not two series 

 as in P. auricoma," and that figures by subsequent authors, 

 e.g. M'Intosh and Malmgren, show the two combs in P. 

 belgica with perfect distinctness. Moreover, certain refer- 

 ences in Pallas's text imply that his species had two distinct 

 combs. Mr. Harvey Gibson concludes that " either Pallas's 

 draughtsman made an error in most of the figures of P. 

 belgica, and failed to represent the comb with sufficient 



1 " Notes on some of the Polychseta," ' First Report on the Fauna of 

 Liverpool Bay,' Lond., 1886. 



VOL. XXVIII, PART 2. NEW 7 SER. S 



