ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
737 
Reproduction of Isopoda.* * * § — Dr. G. Deichmann describes residual 
traces of hermaphroditism in the reproductive organs of Sphaeromidm, 
the form studied being Sphseroma rugicauda. The fact is of obvious 
interest in relation to the typical hermaphroditism of Cymothoidae. In 
discussing the oogenesis of Asellus aquaticus, he describes the formation 
of the brood-chamber from peculiar lamellar appendages developed at 
the base of some of the thoracic limbs. In Porcellio scaber, the lamellae 
are formed in the gap between the hypodermis and the cuticle of the 
thorax, and their formation is restricted to a single moulting period. In 
Asellus, however, the lamellae appear very early as external appendages 
and their complete formation extends over three moulting-periods. It 
seems that the spermatozoa both in Asellus and Sphseroma penetrate as 
far as the ovaries, and that the fertilized ova pass rapidly down the 
oviducts and into the brood-chamber without the occurrence of the 
remarkable processes which are characteristic of the egg-laying of 
Oniscidae. The author describes the typical formation of two polar 
bodies. It has been commonly supposed that the young of Isopoda 
are hatched in the brood-chamber, except indeed in the parasitic 
Anceidae and Cryptoniscidae. But Leichmann finds that in Sphaeromidae 
the development takes place within the. body of the mother in eight thin- 
walled sacs which lie in pairs on the skin of the thoracic sogments by 
the side of the nerve-cord. These sacs are not in direct connection with 
the ovaries or oviducts, they are invaginations of the skin. The eggs 
pass as usual into the space beneath the lamellae, but are transferred 
thence into the eight sacs which have slit-like external apertures. As 
the mass of yolk is insufficient to account for the size of the larva, there 
must be some nutritive supply from the blood of the mother. So too in 
the structure of the lamellae of Asellus aquaticus , Leichmann finds evidence 
that these serve for filtering nutritive constituents from the blood into 
the brood-cavity — an important addition to their acknowledged protective 
function. 
Secondary Sexual Characters in Copepods.f — Dr. W. Giesbrecht, 
answering Prof. Claus, notices a number of omissions in Claus’s 
account of the secondary sexual characters in Calanidse. The omissions 
concern the following genera: — Calanus ( Cetochilus ), Paracalanus , 
Eucalanus ( Calanella ), Glausocalanus ( Eucalanus Claus, non Dana), 
Euchseta, Euchirella ( TJndina Claus, non Dana), Phaenna, and some 
others. 
Distribution of Copepods.f — Dr. W. Giesbrecht adds to a previous 
list a summary in regard to the geographical distribution of the 
Copepoda collected on the “ Yettor Pisani ” expedition. 
New Copepoda.§ — Dr. C. L. Edwards describes five new Copepods 
which he found in the body-cavity of the Holothurian Mulleria Agassizii. 
Three of them are free-living forms, — Pactylopus bahamensis sp. n., Esola 
longicauda g. et sp. n., both belonging to the family Harpacidae, and 
Bhapidophorus Wilsoni g. et sp. n., referable to the family Calanidse. 
* Bibliotheca Zool. (Leuckart and Chun), x. (1891) 44 pp. (8 pis.), 
t Zool. Anzeig,, xiv. (1891) pp. 308-12. 
t Atti R. Accad. Lincei — Rend., vii. (1891) pp. 63-8. 
§ Comptes Rendus, cxii. (1891) pp. 1268-70. 
