40 REVIEW. 
The modifications of the appendages of the feet in the 
thoracic and abdominal regions of the body are more care- 
fully discussed. The elytra of Aphroditacez are considered 
as respiratory organs—certainly not homologous with the 
notopodial cirrhi, since in some genera they exist on the same 
somite with the notopodial cirrhi, as shown by Audouwin and 
Edwards. There can, however, be little doubt that there is 
avery intimate relation between elytra and cirrhi, both in 
structure and function, the absence of cirrhi on those somites 
provided with elytra in most Polynoina sufficiently proving 
this. ‘The elytra are described by M. de Quatrefages as 
composed of two lamelle, in the space between which the 
fluids from the general cavity of the body circulate, passing 
in by a fine aperture in the pedicle of the scale. The cirrhi 
are described as more or less cylindrical and tapering append- 
ages, whose function is that of an obscure sense of touch, 
similar to that of the ‘ whiskers” of certain mammifers. 
Now, though this description of elytra and cirrhi is true 
for general purposes, it does not state the whole case. In 
many Polynoina the two lamelle of the elytra are rendered 
entirely continuous by a tough, fibrous, intermediate structure, 
similar to that which in most cases forms the central portion 
of a cirrhus; no passage is thus left for the circulation of 
fluids, and a hard leather-like plate is formed, on the surface 
of which are papille, having, to all appearance, a sensory 
function. On the other hand, the cirrhi in some Polynoina 
(Antinoé nobilis, from the Channel Islands, and the Gastrole- 
pidia of Schmarda) are excavated, and form delicate 
bladder-like sacs, communicating with the general cavity of 
the body, whilst the foliaceous form and respiratory function 
of the cirrhi in Phyllodoce are well known. . 
The chapter on external form concludes with a minute 
description of the various forms of sete and hooklets met 
with in the Annelida. 
The second chapter, devoted to anatomy and physiology, 
is, perhaps, the most valuable in the work, since in it a 
résumé is given of those numerous and excellent essays of the 
author on various genera of Annelida already published, 
whilst there is much additional matter. It would have made 
the work more valuable had not the author dwelt so entirely 
on his own observations, and noticed more fully those of other 
writers. A large portion of this chapter is, we regret to see, 
necessarily taken up in controverting the claims and opinions 
the same definite sense of structural and functional equivalent which they 
have gained in England. 
