ISO 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
size, covers the hermaphrodite organ, part of the liver, &c., consists of a 
small spire, and a wide coil, and is either quite cuticular or partially 
calcified. The pharyngeal bulb is of immense size, prismatic in form, 
exceedingly muscular, and without mandibles or tongue. The penis 
has a superficial lateral groove, and the large prostate is bilobed or 
simple. The Doridiidae are predacious, darkly but strongly coloured, 
restricted to warm and tropical seas, and include two genera — Doridium 
and Navarchus. Six species of Doridium (four new) and two species of 
Navarchus (one new) are described. 
The Genus Gastropteron.* — Prof. R. Bergh publishes a systematic 
study of the genus Gastropteron , the only type of the family Gastro- 
pteridae, which occupies a somewhat terminal position among the aspido- 
cephalous Steganobranchii (Tectibranchs). 
As to the characteristics of the genus : the anterior body is covered 
by a cephalic disc or shield, whose posterior end projects freely, is very 
mobile, and is evidently a tactile organ; the enormously developed 
pleuropodia are at once distinctive ; the posterior body is short and 
sack -like, and quite free from the hind part of the foot or tail ; along 
the anterior half of the right margin there is a small mantle flap which 
covers the gill and the openings beside it ; in the typical species the 
flap is continued backwards as a mobile flagellum ; the internal shell is 
extremely thin, its large terminal portion covers a great part of the pos- 
terior viscera, its small posterior end is nautiloid with two coils, more or 
less calcified ; the pharyngeal bulb is divided into two parts ; the radula 
has but a few rows of teeth, the stomach is without armature, the glans 
penis has no groove ; the prostate is very long and cylindrical. 
Two species are described, G. Mecheli Blainv. from the Mediterranean, 
and G. pacijicum sp. n. from the Pacific. 
Morphology of Sacoglossa.f — Dr. H. von Ihering, after describing 
more or less in detail various forms, points out that the ordinary doc- 
trine that, in hermaphrodite animals, the sperm and ova mature at 
different times is absolutely false. With regard to the affinities of the 
group the iEolidiidaB are not at all close to it, for they differ in impor- 
tant points of the structure of digestive and genital organs, while the 
dorsal papillae contain branches of a tubular gland. The closest affinity 
appears to be to the Dorididae. 
The author does not seem to be at all satisfied with recent specu- 
lations as to the origin of the Mollusca, and declares, apparently in all 
seriousness, that no explanation remains for him save the supposition 
that the Vermes were derived from the Mollusca. 
Excretory and Reproductive Apparatus of Elysia.j; — Prof. P. 
Pelseneer finds that the most striking character in the renal organ of 
Elysia, and one that is unique among Molluscs, is the multiplicity of 
the reno-pericardiac ducts, of which there are, at least, ten. These 
ducts are short, and have a high ciliated epithelium. The author 
believes that the most anterior or ventral of the pericardiac orifices is the 
* Zool. Jahrb. (Abth. Anat. Ontog.) vii. (1893) pp. 281-308 (2 pis.). 
t Nova Acta Acad. Leop. Car. Nat. Cur., lviii. (1893) pp. 363-435 (2 pis.) Also 
separately, Halle, 1892. J Zool. Anzeig., xvi. (1893) pp. 458-60. 
