QUATREFAGE’S HISTOIRE NATURELLE. 37 
M. de Quatrefages’ classification, and that in Carus’s ‘ Hand- 
buch,’ representing the last German view of these animals ; 
VERS. VERMES. 
(3S SS eS 
DIOiQUES. MonoiguEs. Annulata. 
Annelides. Erythrémes (Oligocheta). 
Rotateurs. Gephyrea. 
Géphyriens. Chetognatha (Sagitta), 
Malacobdelles. Bdelles (Hirudinea). 
Miocelés. Turbellariés. Nematelminthes. 
Nematoides. Platyelminthes,. 
Cestoides. 
Those groups printed in italics in the left-hand table form 
the Annulata of Carus’s arrangement. 
It is an unfortunate thing for M. de Quatrefages’ high 
estimate of the value of the unison or conjunction of the sexes 
as separating characters that Professor Huxley, some years 
since, described a small tubicolate Annelid which had the 
sexes united. M. de Quatrefages, while admitting this as 
rather an awkward hitch in his arrangement, contends that 
such an Annelid was only an accidental exception—one of 
those curious exceptions which prove the rule. This, we 
think, can hardly be maintained in the present very limited 
state of our knowledge of the reproductive organs of Annelida, 
and prefer such an arrangement as that of Carus, which 
should, however, include the Rotifera. 
After thus clearing the way, the author proceeds to deal 
with the class Annelida as limited above. 
His first chapter is devoted to “ external organization,” 
the remarks on the general form of the body and its division 
into regions being well worth perusal. The division into a 
fore part, a hind part, and a middle part—a head, a tail, and 
a thorax—exists in Annelids as in all animals of any com- 
plexity of organization; it is but faintly indicated in the 
errant Annelids whose thorax is not marked off from the tail, 
but in the sedentary forms is most obvious. M. de Quatre- 
fages gives numerous details of the modifications of these 
parts, but hardly seems to recognise the fact that they are 
built up by the modification of homologous somites. In his 
review of the nomenclature of these various parts, and in 
particular those of the cephalic region, it is unfortunate that 
he has not noticed in any way the brief but most clear and 
philosophical view of the structure of Annelida given by 
Professor Huxley in the lectures already referred to. In all 
probability, M. de Quatrefages has never seen these lectures, 
which have been allowed to remain in comparative obscurity 
for more than ten years. 
