Den midterste Del af Centralstrængen er noget tyn- 
dere end den forreste og bagerste Del, og udsender til 
begge Sider en Mængde Grene, hvoraf enkelte staa næsten 
lige overfor hinanden, medens andre alternere, endog med 
temmelig lange Mellemrum, Fig. 16, a. De fleste af disse 
Grene gaa meget snart ind imellem Hudens Muskellag, 
hvor de dele sig, enkelte andre kunne forfølges noget læn- 
gere, førend de tabe sig i Huden. De have ved deres Ud- 
spring en næsten horizontal Retning. 
Efterhaanden som Centralstrengen kommer længere 
fortil, bliver den noget tykkere, Fig. 16,6; den løber imel- 
lem begge Æggebeholderne, Fig. 16, h, h, ved Siden af 
Bugkarret, og afsender lignende Grene til Huden og Me- 
senteriet, som dens midterste Del, kun have de her en 
mere skraa Retning. Naar den kommen lidt foran 
Æggebeholderne, afgiver den paa hver Side en fin Gren, 
Fig. 16, c, der gaar bag til Udforselskanalen for Ægge- 
beholderne. Den afgiver fremdeles mange fine Grene til 
Mesenteriet og Huden, indtil den omtrent 3”” fra Mund- 
aabningen deler sig i to Stammer, Fig. 16, d, der gaar hver 
til sin Side og omfatter den forreste Del af Svælget, hvor- 
efter de forene sig paa dettes Rygside, og danner derved 
en temmelig vid Ring, hvorfra udgaar Grene til Huden, 
Mundhulheden og NSpiserøret, Fig. 16, e. 
er 
Bagtil fortsætter Uentralstrængen sit Lob ved Siden 
af Æggestokken, Fig. 16, f, som for endel dækker den, og 
afgiver en Mængde Smaagrene til Huden, samt flere Grene 
til Mesenteriet og Æggestokken; henimod Anus deler den 
sig, Fig. 16, g, og slaar sig om Endetarmen, hvor begge 
Grene tabe sig ganske i Bindevævet. ø 
Centralstrængen er fuldstændig uden Knuder eller 
Ganglier; den har en temmelig fast Skede, indenfor hvilken 
er et peripherisk cellulært Lag, og et centralt, der er det 
tykkeste, og bestaar af Nervefibriller. Det peripheriske 
Lag synes at være sammenyoxet med Skeden; noget Kar 
findes ikke. Grenene ere sammensatte paa lignende Maade, 
og det har ikke været os muligt at opdage nogen ganglionær 
Dannelse, ligesaalidt paa dem, som paa Centralstrængen. 
Efter Lacaze-Duthiers Undersøgelser over Nervesyste- 
met hos Bonellia viridis synes dette at stemme temmelig 
overens med hvad vi have fundet hos Hamingia; den væ- 
sentligste Forskjel ligger i, at hos denne, som ingen Snabel 
har, nærmer Svælgringen sig mere den for Gephyreerne 
almindelige. 
Professor Greef* angiver, at ifølge hans Undersøgelser 
skal Centralnervestrængen hos Echiwrus Pallasii, Thalas- 
sema Baromii og Bonellia viridis, samt hos mange børste- 
løse Gephyreer være uden Ganglier og indesluttet i et 
1 Sitzungsberichte d. Gesellschaft zur Beförderung der gesammten 
Naturwissenschaften zu Marburg, No. 2, Febr. 1874. 
30 
The medial section of the central nervous chord is 
somewhat thinner than are the anterior and posterior sec- 
tions, and sends off from either side a multitude of branches, 
some of which have their points of origin nearly opposite, 
whereas those of others alternate one with the other, some- 
times at considerable intervals, fig. 16, a. Most of these 
branches very speedily pass in between the muscular layers 
of the skin a few can be traced somewhat farther, before 
they coalesce with the integument. At the point of issue, 
they have all of them a well nigh horizontal direction. 
Gradually increasing in thickness, fig. 16, 0, the 
farther anteriorly it protends, the central nervous chord 
passes between the two uteri, fig. 16, h, h, alongside of 
the ventral vessel, and sends off to the skin and the me- 
sentery branches of the same kind as those issuing from 
its mesial section; they take, however, a more oblique 
direction. , A little anterior to the uteri, it sends forth 
from either side a slender branch, fig. 16, c, which 
strikes off backward to the oviducal canal, or uterine 
duct. It still continues to furnish the mesentery and the 
skin with numerous ramifications, till it divides, about 3”” 
from the buccal aperture, into two principal branches, one 
on either side, fig. 16, d, which, proceeding to the gullet, 
coil round the anterior portion of that organ, and then 
unite on its dorsal surface, forming a large ring, from 
which branches are sent off to the skin, the buccal cavity, 
and the esophagus, fig. 16, e. 
Posteriorly, the central nervous chord protends along- 
side of the ovarium, fig. 16, f, by which it is partly 
covered, and sends off a multitude of ramifications to the 
skin, and several branches to the mesentery and the ova- 
rium; in close proximity to the anus, it divides dichotom- 
ously, fig. 16, g, encircling the rectum, where both branches 
coalesce with the connective tissue. 
The central nervous chord is entirely destitute of 
nodes or ganglions; it is furnished with a comparatively 
firm-textured sheath, underneath which extends a peripheral 
cellular and a central layer, the latter, consisting of ner- 
vous fibrils, being the thickest. The peripheral layer would 
appear to be connate with the sheath: there is no vessel. 
The branches are built up in like manner; and we have 
failed to detect any trace of ganglionous organs either on 
these subsidiary offshoots or on the central chord itself. 
The nervous system in Bonellia viridis, as described 
by Lacaze-Duthiers, would appear to agree pretty closely 
with what we have observed relating to that system im 
Hamingia; the principal difference lies in this, that the 
latter, which is not distinguished by a proboscis, has the 
pharyngeal ring nearer in resemblance to that generally 
met with in the Gephyrea. 
Professor Greef! states, that, according to his obser- 
vations, the central nervous chord in Echiurus Pallasii, 
Thalassema Baroni, Bonellia viridis, and in many other 
asetous Gephyreans, is destitute of ganglions, and enclosed 
1 Sitzungsberichte d. Gesellschaft zur Beförderung der gesammten 
Naturwissenschaften zu Marburg, No. 2, Febr. 1874. 
