SYSTEMATIC ACCOUNT 173 



Discussion. In Apstein's original description of T. planktonis he particularly noted the absence of a 

 first pair of chaetigers but some later authors (Malaquin and Carin, 1922, and Stop-Bowitz, 1948) 

 have noticed their presence in supposedly young forms. From Apstein's illustration it is clear that 

 his specimen, 5 mm. long for thirteen pairs of parapodia, was not fully developed, the chromophil 

 gland being some distance from the pinnule. It is in fact of that size and stage of development in 

 which one would expect a first pair of chaetigers to be present, if they are present at all. In the present 



0'5 mm 



0'5 mm 



0-5 m 



Text-fig. 6. Tomopteris planktonis: parapodia of specimens from (a) St. 1782, (b) St. 254, (c) St. 2316, 



(d) St. 2393, (e) St. 1776, {/) St 254. 



survey, even in the smallest specimens, 2 mm. long for ten pairs of parapodia, there is no sign of a 

 first pair of chaetigers, and I must conclude that the particular specimens to which Malaquin and 

 Carin (1922) and Stop-Bowitz (1948) referred are not T. planktonis; it is possible that they were 

 dealing with young specimens of T. elegans (see pp. 179-180). 



In the course of this work I have re-examined the following material : 



(a) Monro, 1930, p. 87, as T. cavalli, from 'Discovery', St. 89, 1000-0 m. Monro reported four 

 specimens, three of which are present in the B.M.(N.H.), (Reg. no. 1930, 10.8.848-850) all of them 

 in a state of bad preservation ; two have a first pair of chaetigers, the larger, 1 5 mm. long for twenty- 

 three parapodia, has a tail, and the other, 1 1 mm. long for twenty-one parapodia has hyaline glands. 

 Neither of these can be T. cavalli, which was first described by Rosa (1907) without hyaline glands, 

 or a tail, or a first pair of chaetigers. I think they are T. krampi Wesenburg-Lund (1936) (see below, 



