$ 
No. 385.] AEVIEWS OF RECENT LITERATURE. 75 
ing the extent to which they are open to structural variations.’ The 
first species reported on is Actinia eguina, of which 165 specimens 
were examined. In all these the mesenteries were hexamerous in 
arrangement, but in seven, or 4.24 per cent, abnormalities were noted 
in the siphonoglyphs. Four of these seven specimens had one sipho- 
noglyph each ; one had three, and two had two, which, however, were 
not opposite each other. In all cases the siphonoglyphs were accom- 
panied with directive mesenteries, and no such mesenteries were 
found except associated with siphonoglyphs. This enumeration shows 
that A. eguina is far more stable as a species than other actinians, 
such as Metridium marginatum, in which the abnormal individuals 
far outnumber the normal ones. enr 
Dorsal Organs of Arthropods. 
clude that the various structures in the arthropods, — some median 
and others paired, — known as dorsal organs, are cænogenetic in 
character, and have as their function the reduction of the vitellocyte 
layer, while in a few cases it produces a secretion which in Idotea 
fixes the embryo to the chorion. In other cases the secretion may 
serve as a protective layer between chorion and embryo. 
Zoological Notes. — We have already referred to the failure of the 
Senff expedition to northern Africa in its endeavor to obtain mate- 
rials illustrating the embryology of the Dipnoan Protopterus. We 
learn, however, that the University of Cambridge has received a 
large series of embryos of the closely allied Lepidosiren from South 
America, which, we hope, may give us a better knowledge of this 
interesting group. = 
The United States Fish Commission has been actively engaged in 
the study of the tile fish, and this year finds them very abundant 
and extending over a larger range than was known before. 
The discovery of a fourth specimen of the rare rail, Wotorius hoch- 
stetteri, in New Zealand, is announced. 
Goppert concludes, as the result of detailed studies on the laryn- 
geal apparatus of the Amphibia,’ that the whole laryngeo-tracheal 
skeleton — that is the arytenoids and the cricoids, as well as the 
1 Clubb, J. A. The Mesenteries and (Esophageal Grooves of Actinia been : 
Linn. Zrans. Liverpool Biol. Soc., vol. xii, pp. 390-311. . 
2 Biol. Centralblatt, Bd. xviii (1898), p. 736. 
8 Morph. Jahr., Ba. xxvi (1898), p. 282. 
