16 IVAR ARWIDSSON, SYSTEMATIC NOTES ON SOME MALDA NIDS. 



on the left side: about halfway between the normal parapodium and the anterior limit of the 2 nd 

 normal setigerous segment there is to the left a slight indication of a parapodium, bearing weak capil- 

 lary setae. The l st setigerous segment, including the beginning of this extra segment 1 a (of the left 

 side), is longer on the left side than on the right, and in addition the ventral nerve-cord forms a bend 

 to the left opposite the parapodium 1 a. 



In this connection I wish to touch upon the Leiochone sp. mentioned by me at an earlier op- 

 portunity from the Bergen district (Norway) (24, p. 147); there was only one anterior end, com- 

 prising 3 normal setigerous segments and before them a weaker developed one. It now seems highly 

 probable that we have to do here with a specimen of L. johnstoni, in which, however, no ocelli were 

 observed. I interpreted in 1907 the respective segments as the l st — 4 th setigerous ones, the foremost 

 one of which seemed to be somewhat reduced, but possibly normal. I had, however, then no reason 

 to suspect that it might be a specimen with a supernumerary anterior setigerous segment. I still 

 consider it probable that the development of the foremost setigerous segment is not due to incomplete 

 regeneration (ef. 24), as the glands of the anterior part do not show any weakness in comparison with 

 other glands. It is not improbable that this anterior setigerous segment may represent the typic- 

 ally achaetous segment that may be assumed to be present normally behind the buccal segment. 

 If, on the other hand, there really has taken place a reduetion of the segment in question, this 

 would be a considerable one. The uncini of the specimen are somewhat different from those of the 

 normal L. /o/msfom'-specimens with regard to the teeth and possibly also to the occurrence of 

 bristles, but these conditions do not seem to point in any definite direction. 



Epidermal glands. Figs. 7 — 10, etc. give a rough idea of the distribution of 

 epidermal glands. On the head there are strong glands on the keel (especially furthest 

 forward), as well as on the lower side of the cephalic lobe, where they form a band some- 

 what in front of the mouth and also are fairly close on the outside of the borders (especi- 

 ally foremost below). The l st setigerous segment has a weak band of glands furthest 

 forw r ard; on the next segment the same band is considerably stronger, but leaves the 

 anterior edge itself free, as do also the still stronger bands of the 3 rd — 7 th setigerous seg- 

 ments. In the band of the 3 rd setigerous segment and also in the anterior edge of the 

 nearest following bands the glands are especially distinct. Otherwise the anterior part 

 up to the 2 nd setigerous segment inclusive has sparse glands; the 3 rd ~6 th setigerous seg- 

 ments are fairly strongly and uniformly provided with glands behind the parapodia, 

 except the most posterior part of the 3 rd ( — 4 th ) segment close to its limit. The 7 th 

 setigerous segment is certainly provided rather densely with glands behind the para- 

 podia, decreasing, however, in strength. Between the lowest uncini of each pair of 

 parapodia and somewhat surrounding these there is on the 3 rd — 6 th setigerous segments 

 a collection of specially strong glands; on the 7 th setigerous segment there is a rounded 

 collection of similar glands beneath the row of uncini on each side. The ventral nerve- 

 cord is on the lst_2nd setigerous segments, behind the respective band of glands, free 

 on the whole from glands, on the 3 rd setigerous segment somewhat free, especially posteri- 

 orly, but on the 4 lh — 6 th setigerous segments it has on the whole as many glands as the 

 surrounding parts of the respective segments. For the glands of the 8 th setigerous segment 

 see fig. 10; the anterior strong glands — placed in an angle — - on the lower glandular 

 field only appear on rather large specimens. On smaller ones there are bo be seen a short 

 distance in front of the middle uncini, in the same glandular field, round, not stainablc 

 spöts, which are generally well bounded off from the surrounding verv dense, but still 



