ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
481 
Male Gonangia of Distichopora and^Allopora.* — Dr. S. J. Hickson 
finds that the spermatic csecal diverticula of Distichopora are not as long 
and prominent as those of Allopora ; they are usually grouped in threes 
and fours, and lie just beneath the surface, so that, when mature, they 
are quite visible before decalcification. 
Structure and Development of Gonophores. j — Prof. W. K. Brooks 
and Mr. E. G. Conklin give an account of the structure and develop- 
ment of the gonophores of a certain Siphonophore belonging to the 
Auronectae of Haeckel. One result of this investigation is to show 
that the so-called “ polyovone gynophores ” show no trace of medusoid 
structure and are merely pouches containing ova ; such structures are 
therefore spoken of as egg-pouches. 
The structure of the gonophores is so complicated that the authors 
find themselves compelled to describe their development in detail ; in 
which course we have not space to follow them. The chief conclusions, 
however, are : — The egg-pouch must be regarded as a part of the stem, 
w r here the growth of the egg-cells may take place while the gonophore 
is developing. As soon as the gonophore is formed, one of the eggs, 
already quite large, passes into it and lies between the ectoderm and 
endoderm of the manubrium. The egg is rapidly nourished by the 
disintegration of the egg-cells remaining in the egg-pouch, and by the 
formation of large endoderm folds which have a secretory function. The 
whole contrivance is such as to secure as rapid a development of the 
sexual cells as possible, similarly to the cases described by Weismann 
in many Hydromedusae and Siphonophores. 
As female gonophores alone were found, it is possible that the male 
may be very different in form to the female, and it is thought very 
probable that the male of Physalia, if described, has been regarded as 
a very different genus to the female. 
Halistemma in British Waters.^ — The Rev. A. D. Sloan records 
the first Siphonophore found in St. Andrews Bay. Prof. MTntosh, in 
a note to the paper, remarks that Siphonophores are, as a rule, conspicuous 
by their absence, on the east coast of Britain. Diphyes, Physalia , and 
Velella are occasionally found in the British seas. 
Development of Cyanea arctica.§ — Prof. J. Playfair M £ Murrich has 
had the opportunity of studying the development of Cyanea arctica, 
which was very abundant last May in Vineyard Sound. Segmentation 
is practically regular, and a blastula is formed ; there is a transient 
pseudogastrula. A solid planula is formed by the immigration of cells, 
and this consists of an outer layer of columnar cells and a central mass, 
in which cell-outlines cannot be made out in sections. After some 
swimming about, the embryos settle down and inclose themselves in a 
circular plano-convex cyst. While within this the central mass becomes 
hollowed out and the endoderm is formed. After several days the 
embryo emerges from the cyst through an orifice formed apparently by 
solution. 
* Rep. Brit. Assoc., 1890 (1891) p. 864. 
f John Hopkins Univ. Circ., x. (1891) pp. 87-9 (1 pi.). 
X Ann. and Mag. Nat. Hist., vii. (1891) pp. 413-6 (1 pi.). 
§ Amer. Nat., xxv. (1891) pp. 287-9. 
