ANATOMY OF AT^ENICOLA ASSIMILTS. 765 



time the occurrence of several pairs of oesophageal ciBca was 

 known only in this species, and, indeed, was considered to bo 

 one of its most characteristic features. At the same time I 

 looked for the otocysts, but did not succeed in finding* theni.^ 

 They would have been moderately easy to see in post-larval 

 stages of A, marina of the same size, and finding no similar 

 structures in my post-larva3 I therefore concluded (wrongly, 

 as it now appears) that otocysts were absent. With these 

 two features in mind, but relying especially on the very 

 obvious presence of several oesophageal pouches, I identified 

 the specimens as post-larval stages of A. claparedii, and as 

 such they were recorded by Miss Pratt (1901, p. 12). The 

 fact that these specimens had been obtained in the region in 

 which A. assimilis is found had not escaped my notice, 

 but as Ehlers' account (1897, pp. 103, 104) stated that his 

 species closely resembled A. marina, it was naturally 

 concluded that the presence of multiple oesophageal glands 

 might still be regarded as a diagnostic character of A. 

 claparedii. 



These post-larvie have now been carefully re-examined, 

 both entire and in sections, with the result that my previous 

 determination is found to be wrong; they are the youug 

 stages of A. assimilis, var. af finis. 



The three specimens were found on the surface of the sea 

 near the Falkland Islands, by Mr. R. Vallentin, of New Quay, 

 and were handed over to me by Miss Pratt, of Owens 

 College, Manchester, who was working over Mr. Vallentin's 

 collection of Polychastes. 



The specimens are 7'6, 8*7, and ll'l mm. long respectively. 

 The largest specimen is provided with a transparent gelatin- 

 ous envelope about 1 mm. in diameter, which covers the 

 animal, except for a distance of a little over a millimetre at 

 each end. In general aspect these post-larva3 resemble 

 those of A. marina. 



' The nepluidiopores were also examined, but on account of their minute size 

 it was impossible to make certain of their presence or absence on the critical seg- 

 ment (the fourth), and therefore their number could not, be definitely ascertained. 

 VOL. 46, PAKT 4. NEW SKKIKS. D D D 



