336 THE DOLABELLINAE. 
7a, 7b, and 7c, of the seventh pedal nerve, 7 ped., form anastomoses as follows:— _ 
the branch 7a ramifies among the tubules of the organ of Bohadsch, o. B, also — 
sending a branch to unite with the nerve /a from the first parietal nerve, p. 1; 
7b sends numerous branches into the organ of Bohadsch, o. B, and finally unites — 
with the recurrent branch 2c of the second visceral nerve; while 7c, the more 
anterior terminal branch of the seventh pedal, sends twigs to the dorsal peri- 
toneum, and anastomoses with a delicate median branch of the second parietal 
nerve, which is distributed to the same region. These relations are substantially 
the same as those brought out by the writer (1909, p. 53) for Tethys dactylomela 
and Tethys cervina, in which forms the organ of Bohadsch is shown to be inner- 7 
vated from both the right pedal and the left visceral ganglia. Plate 3, fig. 1 
illustrates this arrangement for T. cervina. Here the third pedal nerve 3 ped, 
sends the branches 3a and 36 to the organ of Bohadsch, o B, which is also inner- 
vated by the recurrent anastomosing branch 2c, from the second visceral nerve, 
v2, of the left side. In Mazzarelli’s (1890), study of the organ of Bohadsch in 
the Mediterranean Aplysiidae he describes the innervation as from the right 
pedal ganglion alone, and disputes the earlier statement of Vayssiére (1885) as" 
to its innervation from the left visceral ganglion. The present writer’s previous 
position that both authors were in part correct is much strengthened by this 
similar condition of double innervation, found in the more distantly related — 
Dolabellinae. 
The eighth pedal nerve, 8, arises just behind the sixth one, from the pos- — 
terior outer margin of the pedal ganglion. It is of moderate size, and passes 
backward and dorsally along the body-wall, sending occasional branches to the 
retractor muscles of the head. The main nerve bifurcates as it enters the 
dorso-lateral body-wall, about midway of the length of the animal, its further 
subdivisions passing mainly to the parapodia. Two small anastomosing — 
branches are also given off to the posterior subdivision of the seventh pedal — 
nerve, before the latter reaches its distribution in the organ of Bohadsch. 
The ninth, or posterior pedal nerve, 9, is the largest nerve from the pedal . 
ganglia. It arises from the posterior border of the ganglion and passes backward 
below the head retractor muscles to the posterior region of the foot, where 
it ramifies among its muscles and those of the adjacent body-wall. Close 
to the origin of the ninth nerve on the left side, but some distance from that — 
point on the right one, a slender branch, 9a, is given off. On each side the 
fibres of this delicate nerve may be followed back in the common trunk to the — 
pedal ganglion. Upon the right side this branch forms an anastomosis with a 
