ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
305 
Pontoscolex. They were first described by Perrier (187* * * § 2) as unicellular 
glands. They are highly differentiated, with associated nerve-endings or 
ganglia (not very satisfactorily proved), and each contains a peculiar 
globular body towards the outer side. “ The cell seems especially con- 
structed so as to keep this otosome in place, confined to the upper 
vacuole, while the beautiful protoplasmic structure below it might serve 
to propagate the sound-waves to the nerves below. The central cyto- 
plasmic floor, which always seems to be in the same tension as regards 
the cell-walls, and always in the same position to the base of the cell, 
may serve as a kind of sounding-board.” It is also principally in the 
equatorial of this floor that the supposed ganglion-cells or nerve-plates 
are situated. Eisen describes Pontoscolex Lilljeborgi sp. n. from Guate- 
mala, and a Mexican variety of P. coretJirurus F. Muller. 
Pelagic Polychaete Larvae.* — Dr. Y. Haecker distinguishes (a) the 
resident forms, ( b ) the regular visitors, and (c) the casual intruders. 
(a) In the first place there are the larvre of many Polychaeta which 
are, so to speak, at home in the open sea, — various Phyllodocidae, Alci- 
opidae, Tomopteridae, &c. Most of the larvae, as Keibisch has pointed 
out, soon lose their ciliated rings, and acquire more effective locomotor 
and sensory appendages. They tend to suppress the trochophore and 
metatrochophore stage, and to pass directly to the Neetochaeta stage. 
(b) The second set includes those which are normally pelagic during 
a certain period (at least) of their larval life. Especially well adapted 
are the Nitraria and It os tr aria types, which are discussed at some length. 
Their remarkable adaptations which increase their capacity for drifting, 
and their power of energetic movement, are illustrated. 
(c) The third set includes wanderers from the littoral plankton. 
They are the larvae of various errant and tubicolous forms, and have 
been swept out from the shore. They are “ lost children,” and most of 
them must perish. 
Polychseta of French Coast.f — Baron de St. Joseph concludes his 
valuable systematic account of the Polychaeta found off the French 
coast. 
Ampharetidae.J — Pierre Fauvel describes Ampharete grubei Malmg. 
in detail, and deals more briefly with some related forms. The family is 
in many ways more nearly related to the Terebellidm than to the Am- 
phictenidse ; the three families are parallel branches from an unknown 
starting point. 
Spirorbis.§ — MM. Maurice Caullery and Felix Mesnil give a syste- 
matic account of the (28) species of Spirorbis, which they arrange in 
sub-genera. The genus is a Serpulid in which the number of thoracic 
segments shows the maximum reduction (to 3), and the coiling of the 
tube has become constant. With the spiral coiling of the tube an 
asymmetrical structure of the body is associated. In the phylogenetic 
* Biol. Centralbl., xviii. (189S) pp. 39—54 (9 figs.). 
t Ann. Sci. Nat. (Zool.), v. (1897) pp. 225-464 (11 pis.). 
t Bull. Sci. France Belg., xxx. (1897) pp. 1-212 (11 nls.). See Zool. Centralbl., 
iv. (1897) pp. 866-8. 
§ Tom. cit., pp. 185-233 (4 pis.). See Zool. Centralbl., iv. (1897) pp. 865-6. 
Y 2 
