148 REVIEWS. 
ciated groups into juxtaposition, although no constant structural differ- 
ence has yet been discovered by which to separate them 
The partially natural basis on Md the system of Nitzsch is ie is 
clearly recognized by Dr. Coues, although the dat ejiis which it was 
founded have thus far been but very imperfectly pres 
n regard to the quinary system of Vigors, mons d wrong 
in its assumptions, especially as developed by some of Vigors's followers, 
Dr. Coues justly finds (as the present writer has been long of the opinion 
there existed) many facts that to a certain extent favor this arrangement 
in regard to many of its details. The remarkable vitality of the system, and 
its strong hold upon public opinion, as Dr. dut ues diete is evidence 
that it has some foundation in nature f which it was able 
for a long period to hold its ventana aan the numerous technical ob- 
onward when the idea of a ** lineal" classification was abandoned; and it 
was doubtless the advantages of the ‘‘circulatory " system of grouping, 
and the recognition of similar modifications of the members of diverse 
groups that gave to the Vigorean system some of its recognized advan- 
tages. Dr. Coues, however, goes further: **A system," he says, ‘‘ that 
disposes objects in — planes is a great advantage over a lin- 
eal arrangement, but it stops half-way to the goal. The third dimension 
is needed; to me - breadth must be added thickness; the circle 
must vijei & sphere: . ... . We cannot predicate affinity or anal- 
ogy o o the ia or left, ie She top or bottom,— but must take it 
that id lai near or remote, may approach, touch, or fuse with each 
other, along the axis of either of the three possible diameters” (p. 197). 
The idea h 
u 
tion (though not necessarily implying generic relationship) —is one that 
has doubtless impressed the majority of naturalists, and which has given 
rise, in the various efforts made for its expression, to I numerous and 
s The met 
physical form in which Dr. Coues expresses this idea aia to it, doubt- 
less, to many minds, a somewhat objectionable charac 
In reviewing Professor Huxley’s classification, Dr. Coues terms it ‘‘ an 
attempt ” — as a slight examination of it is sufficient to show — ** to clas- 
certain character, the value of which was not only unknown, but also 
unsuspected before; and has shown how perfectly it marks groups of à 
