Die Kiemen. 937 
central support (shank) of the T-shaped structure, while the branchial laminae, passing from 
the transverse bar as long recurved processes, correspond to the flukes. At the junction of 
the septal rod with the transverse portion is a slight swelling of the former, having the brown 
chitinous part in the centre, the rest of the process, as well as the branchial laminae, being 
quite translucent. As the sections proceed outwards, however, a slightly brownish hue from 
the presence of dense chitinous matter is seen at the base of the branchial laminae when 
they join the septal rod. The latter is marked almost from the commencement by 
a vertical median line, showing its double composition« [vgl. Taf.19 Fig.23 sz]. »The 
branchial laminae at this part touch at the lower edges, but gape at the upper, so as to 
make a triangular channel, which is completed by the thick membrane of the region. Further 
outwards the branchial arches stand freely in their grooves, their supporting 
chitinous laminae« [vgl. Taf. 19 Fig.23 dz] »being enlarged at the upper end and bent 
inwards in transverse section, and the tunnel completed by the membrane formerly 
described. The supporting chitinous rods gradually taper from the median line to the outer 
edge, as also do those of the septal regions; thus the diminution in the former case has to 
be compensated by an increase of the soft parts of the tunnel. After the branchial 
lamella forms an independent sabre in the groove, the septal process is found (in 
transverse section) elevated on a still higher fold of the mucous membrane as a 
club-shaped structure« [vgl. Taf. 19 Fig. 23 sz], »the central brown chitinous part — somewhat 
triangular in shape — appearing in the rounded summit. The next change is the increase 
of the brown hue in the chitinous supports of the branchial lamellae. 'The double nature 
of the septal process also becomes more evident, even from the fold of membrane upwards. 
The summit, however, is till uniformly coated by the investing membrane of the branchial 
region; by-and-by the papilla on which it is placed shortens, and the pale chitinous 
tips of the rods split to form the arch at the boundary« [vgl. Taf. 19 Fig. 24 s2]. 
»The laminae of the branchial processes diminish into slender pale chitinous rods, which lie 
towards the inner (lateral) margin of the canal, and each soon terminates in a closed extremity. 
Over the whole of the processes just described a thick mucous layer, probably ciliated during 
life, is spread. — — The foregoing account, of course, is only meant to convey a description 
of the framework of the branchial apparatus. — — The arrangement of the system in this 
form shows a close approach to that of Balanoglossus clavigerus.« 
Diese Darstellung ist, abgesehen von einigen untergeordnetern Einzelheiten, so durch- 
aus richtig, dass ich ihr nur wenig hinzuzufügen hätte, wenn sie nicht so ausserordentlich 
wenig anschaulich wäre, dass ein nicht mit dem Gegenstande durch eigne Anschauung 
vertrauter Leser kaum im Stande sein dürfte, sich eine einigermaassen klare Vorstellung 
von dem beschriebnen Apparat zu bilden. Muarıon begnügt sich mit der Wiedergabe einer 
Zeichnung, die ein Stück eines Längsschnitts und zwar eines der Medianebene ziemlich 
nahen Sagittalschnitts darstellt, eine Kiementasche und Theile der beiden angrenzenden um- 
fassend (p. 325 fig. D). 
