ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
43 
third cleavage establishes the separation of the two primary layers, for 
the four dorsal blastomeres form endoderm and the four ventral ectoderm. 
Julinia.* — Under this name Mr. W. T. Caiman describes a new genus 
of Compound Ascidians from the Antarctic Ocean, attention to which 
was attracted by the large size and remarkable appearance of its single 
representative, which is called J. australis. The colony is irregularly 
cylindrical, 78*5 cm. long and from 1*5 to 2*5 cm. in diameter. A 
detailed description is given of its anatomy, and, taking the present 
definition of families, it is judged to have its nearest affinities to Distaplia. 
A systematic definition of the genus is given. 
Mollusca. 
Shells from the Great Lagoon, Watling Island, Bahamas. f — Mr. 
W. H. Dali finds that the Molluscs from this island belong to two 
categories, those which live in the lagoon, and those which live on its 
shores. The marine forms which live in the waters of the lagoon are all 
more or less peculiar, and seem to indicate by their characters that they 
have been derived by a more or less direct modification from recent 
species living normally in the sea about the island. The number of 
species is small, but all are marked by tenuity of shell, diminutive size, 
and, when coloured, by a relatively brilliant colour. 
The terrestrial species are certainly less influenced by the special 
condition of the lagoon than those which live in its water, but they are 
not without their peculiarities. Most are very local ; the presence of a 
Planorbis , the only representative of a freshwater fauna, is very 
interesting. 
Hermaphroditism in Mollusca.J — Dr. P. Pelseneer discusses the 
question of hermaphroditism in the Mollu?ca, where it occurs in every 
class except the Cephalopoda and Scaphopoda. It is remarkable that 
there is very great diversity in the structure of the hermaphrodite gland 
of these classes, and four chief types can be distinguished. 
(1) The undifferentiated gonad, i. e. with acini completely hermaphro- 
dite, is seen in Valvata , a great number of Tectibranchs, almost all 
Pulmonata, and two species of Ostrea. There are some indications of 
specialisation in the Neomeniidae, where each gonad generally gives rise 
to male products towards its lateral face, and to ova towards its axial 
face. 
(2) Gonad with separate male and female acini, but not separate male 
and female regions; this is seen in various Tectibranchs, Nudibranchs, 
and others. In various Nudibranchs the female acini are the most 
superficial. 
(3) Gonad with separate male and female regions, and a common duct ; 
this is seen in Pecten , where the male and female regions are contiguous, 
and in the Cycladidse, where the two regions are fairly separated. 
(4) Male and female portions in the same individual entirely distinct 
from one another, and with special ducts. The vas deferens and oviduct 
may open into a common orifice, as in the Poromyidae, or there may be 
* Quart. Journ. Micr. Sci., xxxvii. (1894) pp. 1-17 (3 pis.). 
t Bull. Mus. Comp. Zoo]., xxv. (1894) pp. 113-24 (1 pi.). 
I Quart. Journ. Micr. Sci., xxxvii. (1894) pp. 19-46 (3 pis.). 
