of Edinburgh, Session 1875 - 76 . 125 
As we proceed backward, the lateral longitudinal muscles gradu- 
ally increase in breadth, while the great oblique bands nearly meet 
in the central line interiorly. The dorsal longitudinal fibres are 
grouped in two symmetrical masses, and a strong band passes 
between the edges of the ventral longitudinal muscles, — the median 
longitudinal fibres formerly indicated lying immediately within 
this layer. The nerve-cords have now descended quite to the 
ventral surface, and have a pale intermediate area. 
As soon as the body assumes a transversely-elongated form, the 
dorsal longitudinal muscles become much extended, and are, be- 
sides, intersected by the powerful vertical bands, which sweep from 
the dorsal basement-layer to the ventral surface, through the lateral 
longitudinal muscles (now for the most part ventral in position). 
The oblique muscle on each side is more horizontal, passing from 
the inferior bristle-bundle to the median line at the ventral surface, 
and going right through the vertical bands before insertion. The 
nerve-cords lie close together below the transverse muscle, and a 
small neural canal exists at the inner and upper border of each. 
There are still a few longitudinal fibres between the ventral attach- 
ments of the oblique muscles. The alimentary canal shows internal 
circular and external longitudinal fibres. 
It is very soon apparent, in proceeding backward, that the 
vertical muscles descending from the dorsal to the ventral surface 
do not interdigitate with the great longitudinal muscles through- 
out their whole extent. They leave, as observed by the lamented 
M. Claparede, at the external border of each dorsal muscle a con- 
siderable mass, which bends downward, and presents in transverse 
section a distinctly pennate appearance. A similar arrangement 
occurs at the outer and inner extremities of the ventral longitu- 
dinal muscles. Finally, the nerve-cords now have a single and 
very large intermediate neural canal. The foregoing condition 
continues with little modification to the tip of the tail ; though the 
dorsal pennate process disappears, the muscle itself being separated 
from its fellow, and considerably diminished in bulk, while the 
transverse fibres between it and the hypodemi have greatly in- 
creased.* 
* The late M. Claparede, in his “ Structure des Annel, S4dentaires,” p. 15, 
&c., pi. xv., gives the structure of the hypoderm, and notices the pennate 
