M. A. de Quatrefages on the Classification of the Annelides. 15 
I will terminate these generalities by a last observation. The 
simple statement of the preceding facts would suffice to enable 
us to conclude with certainty that the relations existing between 
the different groups of the class of Annelides are extremely mul- 
tifarious. Even if we confine ourselves to the families, it must 
be evident that any linear classification is absolutely incapable 
of giving a real idea of these relations; and a glance at the fol- 
lowing Table places this conclusion beyond a doubt. We can- 
not arrange these twenty-six families either in a single or in 
several series without the interruption of zoological relations 
more or less intimate. The arrangement on a single plane 
attempted by Grube is equally mcapable of giving even an ap- 
proximate idea of these relations. To arrive at this, it would be 
indispensable to have recourse to the muitiple superposed planes 
so justly proposed by M. Chevreul. 
The consequence to be drawn from this fact is, that there 
always enters a certain arbitrary element into the relative posi- 
tion of the groups which the necessities of nomenclature compel 
us to arrange in a series. J can therefore easily understand that 
some of my confréres may find fault with the order that I have 
adopted; nevertheless I think I may say that an arrangement 
which enables us to ascertain, even by a very rapid examination, 
the principal general facts above indicated, must at least present 
some advantages. 
Class ANNELIDA. 
(2 Orders, 4: Suborders, 26 Families.) 
Order I. Errarica. 
Regions of the body similar. 
Po Serments dissimilar 0... éen.scscaonacossene Suborder I. KE. ABERRANTES. 
PRONE CLV GEAR dere tater sarees endesskcisesdeeseavese sans 1. Aphroditea. 
ep Wathout clytra: a. tetecsswe xo resdeassenceesaswaseondes 2. Palmyrea. 
II. Segments similar or subsimilar........... Suborder II. E. propria. 
A. No rotatory apparatus. 
a. Buccal armature complex. 
PAGER DESUCN SE! cia tic) cieud danacew ec srs onset 3. Eunicea. 
jTmWathout branchicas se aaciesis ie cs cele 4, Lumbrinerea. 
b. Buccal armature simple or none. 
* ead of ordinary form. 
#. With true branchie. 
a. Branchiz somatic. 
** Branchie arborescent............... 5. Amphinomea. 
Tt Branchiee cirriform, short. 
woe. No-true tentacles iey<s ose veesunaes 6. Nephthydea. 
BB. With true tentacles ............006 7. Nerinea. 
§§ Branchie cirriform, elongated ...... 8. Cirratulea. 
Da. Branchize CGP RRC seas sccscasensitesvenes 9. Chloremea. 
B. No true branchie. 
a. One pair of jaws and some denticles... 10, Nereidea. 
