50 
Archives du Museum d’Histoire Naturelle publiees par lesProfesseurs- 
Administrateurs de cet etablissement. Tome ix., liv r 4 feme . 
Paris, 1856—7* 4 to .—From the Museum. 
Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften. 
Mathematisch-Naturwissenschaftliche Classe, Band xxiii., heft 
2, xxiv., hefte 1, 2 ; Philosophisch-Historische Classe, Band 
xxiii., hefte 1, 2, 3,4. Wien, 1857. 8vo. — From the Vienna 
Academy of Sciences. 
Denkschriften der K. Akademie der Wissenschaften. Mathematisch- 
Naturwissenschaftliche Classe, Dreizehnter Band. Phil.-ITist. 
Classe, Achter Band. Wien, 1857. 4to. — From the same 
Academy . 
Monday , 4th January 1858. 
The Right Rev. Bishop TERROT, V. P., in the Chair. 
The following Communications were read : — 
1. On the Structure of the Reproductive Organs in certain 
Hydroid Polypes. By Dr Allman. 
Most of the observations contained in the present communica- 
tion were made some years ago, and during the last autumn the 
author had an opportunity of repeating many of them and of adding 
some others. His object in now bringing them together was, that 
by being thus placed in possession of sufficient material, we might 
be enabled to make a useful correlation of the ascertained facts, so 
as to obtain, if possible, some more general expressions for the phe- 
nomena presented. 
To arrive at such results, it was found absolutely necessary to in- 
troduce some new terms ; for in many cases, parts requiring precise 
notions had no distinctive appellation whatever, while in other cases 
they had been known by names which convey an entirely false idea 
of their nature and significance. 
Definition of Terms. 
The parts of the hydroid zoophytes, on which devolve the office of 
perpetuating the species by the exercise of a true generative function, 
