KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 40. N:0 4. 11 



If we uow pass on to the Saccosoma, a critical examination of the text and figures 

 of Danielssén and Koren makes it probable, that the genus may be referred to those ani- 

 mals which are related to the Echiurids. However, it must be admitted that its true posi- 

 tion still remains dubious on account of the incompleteness of our present knowledge. 



The Norwegian authors themselves say : Of this genus, too, our description is 

 in some respects, we regret to say. confessedly incomplete, referring as it does to a 

 single specimen, the only one j^et obtained. Besides, the small size and delicate or- 

 ganisation of the animal neeessitating the greatest care in handling, its anatomical- 

 histological investigation, however incomplete, has proved a toilsome and perplexing 

 task. 



Danielssén and Koren referred the Saccosoma to the family Bonellidse. Con- 

 sidering, however, the great differences which appear to exist between Saccosoma and 

 Bonellia I prefer until further to keep them into separate families, Saccosomatidce and 

 Echiuridse. Thus, for instance, the Saccosoma seems to lack a true proboscis, similar 

 to that in the Echiurids, both its mouth and the opening of its single segmental 

 organ being situated in the extremity of the anterior, cylindric portion of the cucurbit- 

 like body. Furthermore, according to the Norwegian investigators, it should be in 

 want of every traces of hooks and bristles and, besides, of the paired tubular or 

 saccifomi organs which open into the rectum and are characteristic of the Echiurida. 



Now it remains to examine the statements of the two Norwegian investigators 

 as regards their genus Hamingia, referred by them to the family Bonellidse. They 

 accept, namely, this family as coordinate to the Echiuridse, which seems to indicate 

 that they consider Hamingia to be closer related to the genus Bonellia than to 

 Echiurus or Thalassema. To my thinking its nearest relatives might be looked for 

 among the genera last mentioned, more especially among the representatives of the 

 genus Thalassema. Nevertheless the distinctions between them are such, that they 

 may be of generic value. 



Thalassema is in possession of a well developed proboscis. Hamingia, on the 

 contrary, should according to .Danielssén and Koren lack a true proboscis in the 

 place of which there should be a dunate, somewhat prominent fold round the mouth». 

 In the text Danielssén and Koren say: Round the buccal opening extend two 

 lunate cutaneous folds, figs. Ib; 2b, rather prominent on the dorsal surface, and a 

 little apart, whereas they gradually converge on the ventral surface, and form an 

 obtuse angle, fig. 2 c, leaving a small portion of the mouth which the said folds do 

 not encircle* . . . »These folds may be regarded as a rudimentary proboscis.» 



In spite of these statements, there still existed some doubts whether there really 

 had not been a true proboscis which by chance had got löst. I myself was streng- 

 thened in this supposition since Horst (1881) evidently entertained the same suspi- 

 cion in regard to the proboscis of his H. glacialis, a form caught in the arctic sea 

 at a locality not very distant from that, where Danielssen and Koren obtained 

 their H. arctica, and doubtlessly identical with it, a view already alluded to by 

 Levinsen (1882 & 1883). In his paper Horst writes: »Die Länge des kopflappens 

 ist 4 mm., nur wird das Vorderende nicht von der Haut iiberdeckt, waraus ich 



