REPOET ON THE NHDIBRAN CHI AT A. 
o 
Phylliroe atlantica, Bergh. 
Phylliroe bucephala, Souleyet, Voy. de la Bonite, Zool., ii., 1852, p. 399-415, pi. xxxv. 
figs. 1—1 8. 1 
„ atlantica, Bergh, Verhandl. d. k. k. zool. -hot. Gesellsch. Wien, Bd. xxi., 1871, pp. 
1302-1305. 
„ ,, Malacolog. TJntersuch., loc. cit., pp. 212-231, Taf. xxviii. figs. 1-18, xxix. 
figs. 1-15, xxx. fig. 1, xxxi. figs. 1-2. 
Sacci hepatici posteriores medio non coarctati. Glandulse hermaphrodisiacse pagina 
inferiore castanese. 
This species differs from that of the Mediterranean in the absence of the constriction 2 
in the middle of the posterior hepatic sacs, and in the chestnut-brown colour of the under- 
side of the hermaphrodite glands. 
A series of thirteen individuals was taken on the surface in the Atlantic near the 
coast of Africa, 16th August 1873, and off St. Vincent, Cape Verde Islands, 26th April 1876. 
Most of the specimens were well preserved and of medium size, the length averaging 
1 2 mm. (without the rhinophoria), and the height 9 mm. ; a few were smaller, not 
measuring more than 8 ‘5 mm. in length. The colour quite as usual. 
The form of the animals and the structure of the organs of the body agree perfectly 
with the previously examined specimens. 
The central nervous system has been already described by me. H. von Jhering 3 
considers that the upper pair of ganglia represent the cerebral, and the lower pair the 
pleuropedal (visceropedal). I do not believe this interpretation to be right, since the 
upper ganglia sometimes exhibit a very marked line of division into two parts, and 
occasionally the upper commissure between the two ganglia is distinctly double, which 
appears to indicate a separate connection between the two cerebral on the one hand, 
and the two pleural ganglia on the other. The upper ganglia give off two strong 
nerves to the walls of the upper part of the body. The visceral commissure certainly 
in most cases appears to be derived from the inferior ganglia, but the same is the case 
with the sub-cerebral commissure, which nevertheless has its origin in the upper ganglia. 
The genital nerve, described by von Jhering, is not the true nervus genitalis but 
the right nervus pediaeus ( longus ), which, passing between the windings of the sper- 
matic duct, extends along the walls of the lower part of the body. The true nervus 
genitalis does not seem to be derived from the inferior ganglia. I never saw the 
commissures uniting the inferior ganglia quite so distinct from each other as von 
Jhering 4 figures them ; the visceral commissure was always free, but the other two 
1 The true Pliylliroe bucephala of Lesueur and Peron inhabits the Mediterranean (Bergh, loc. cit., p. 231). 
2 In two small individuals, measuring 5 to 6 mm. in length, the underside of the glands was not coloured, and the 
hepatic sacs had several constrictions. Are these specimens really Phylliroe bucephala ? (Bergh, loc. cit., p. 235). 
3 Vergl. Anat. d. Nervensyst. d. Moll., Leipzig, 1877, pp. 185-189. 4 Loc. cit., Taf. ii. fig. 5. 
