NEREIS ZONATA. 467 
most is represented by a single horny point, as in Marenzeller’s specimens. The groups in 
IT. are somewhat smaller individually, and apparently less numerous than in N. pelagica. 
III. forms a longer transverse band of more minute denticles, and group IV. is composed 
of more acute paragnathi in a double curve, the inner formed of smaller denticles. V. is 
absent, as in NV. pelagica, and VI. forms a group of smaller denticles than in N. pelagica on 
the elevations at each side. This group is very variable in N. pelagica, occasionally only 
a single large denticle being present on each side, and in all cases the paragnathi are larger. 
VII. and VIII. form the basal row in extrusion, and no groups differ from the homologous 
parts in NV. pelagica more than these. VII. shows the two largest paragnathi in the series 
constituting a basal band in extrusion, and which (band) differs from that of N. pelagica 
in the isolation of the larger distal and the minuteness of the proximal denticles. In N. 
pelagica the large distal paragnathi are much more numerous and less regularly arranged, 
and the proximal smaller denticles are likewise in greater numbers. Side by side the contrast 
between the two is noteworthy. 
In glancing along the feet of the two forms the rounded and blunt condition of the tips 
of the processes in N. pelagica distinguish it, for in N. zonata the lobes are much more acute, 
and Malmeren’s figures originally indicated this clearly. 
Pte. 172.—Proboscis of Nereis zonata. After Malmeren. 
_ Nereis zonata, Malmgren, var. persica, Hauvel, occurs in the Persian Gulf, and has lately 
been carefully described by Prof. Hauvel! both in the ordinary and epitokous conditions. 
The author also states that he considers Nereis procera of Ehlers to be the same species, 
and so with Nereis pulsatoria of Grube. He concludes that Heteronereis grandifolia ¢ , 
Malmgren (Heteronereis assiemilis, Rathke), is the epitokous condition of Nereis zonata. N. 
zonata appears to have a very wide distribution both off the Atlantic and Pacific shores. 
The epitokous forms of Nereis pelagica are distinguished from those of N. zonata by the 
coloration, the latter having light transverse bands which are not present in the former, 
and the paragnathi of groups I. and VI. In N. pelagica the lobes of the feet are evenly 
rounded, whilst in N. zonata they are triangular and run out to a broad point. Ditlevsen, 
who has recently written on the subject, further notes that in N. pelagica the terminal 
processes of the bristles are shorter and more curved than in N. zonata. The author disagrees 
with Michaelsen’s view that Heteronerers arctica of Girsted is the female epitokous form of 
N. zonata, and therefore thinks that the title N. zonata should stand. Moreover, whilst’ 
N. pelagica is generally a littoral species, NV. zonata is procured by the dredge.” 
1 “Arch. Zool. Hxpér.,’ vol. xlvi, p. 382, pls. xix and xx (April, 1911). 
* Herpin has studied the lymphocytes in the perivisceral chamber of Nereids, and considers 
that they nourish the slowly-developing eggs. Moreover, he thinks that the presence of ova in an 
annelid does not prove that the animal is adult (‘Comp. Rend. Acad. Sc. Paris,’ July 25th, 1921). 
229 
