REVIEWS—CONTRIBUTIONS TO NATURAL HISTORY. 173 
guished naturalists have been disposed to connect with the Tunicated 
Molluses, whilst at the lower extremity of the class he not only 
takes in the Hydroid Polypes but the Millepore and several other 
forms. He concludes the portion of his work forming the genera] 
introduction by an account of the various attempts at the classifica- 
of these animals, which is very valuable to the student, who could 
not without great difficulty have collected for himself the scattered 
materials. The remainder of the present volume is devoted to the 
first order of Acalephe, Ctenophore. Their structural features 
must not be allowed to detain us farther than by a single short 
quotation to mark the character which gives them their name: 
(p- 164.) 
“One of the most apparent peculiarities of the Ctenophore, consists of eight 
rows of locomotive flappers, extending along the eight vertical and peripheric 
chymiferous tubes, with which they are closely connected. As far as I can ascer- 
tain, all Ctenophorz have eight such rows, though some of them are represented 
with only four and others with twelve. But their close connection with the 
ambulacral tubes, and the constancy of the number of these tubes in all the 
Ctenophore which I ever had the opportunity of examining, lead me to take it for 
granted that the typical number of the vertical rows of locomotive flappers must 
be eight. Iam inclined to ascribe the conflicting statements upon this point to 
the marked inequality observed among these rows in different families. The fact 
is, that while they are all eight, of equal length and equal prominence in certain 
representatives of this order, in others there are four larger, longer and more 
prominent ones, and four shorter and smaller ones, differing more or less in their 
course. I hold, therefore, that the smaller rows may have been overlooked in 
those genera which are described as having only four rows of locomotive flappers; 
and that in those which are represented as having twelve rows, the vibratile cilia 
of the epithelial cells lining the digestive cavity, may have been mistaken for 
additional rows of locomotive flappers. Gegenbaur gives the same explanation of 
the singular figure of the Alcinoe papillosa of Delle Chiajé. The close connection 
which exists between the rows of locomotive flappers and the chymiferous tubes 
is so similar to the general organization of the ambulacral system of the Echino- 
derms, that I do not hesitate to consider these structures as homologous.” 
Passing by all that relates to the sub-orders and families of Cteno- 
phore, and proceeding to the North American species, we must 
indulge ourselves in a descriptive quotation well fitted to excite the 
curiosity and admiration of every reader : 
‘There can be searcely anything more beautiful to behold than such a living 
transparent sphere sailing through the water, coursing one way or another, now 
slowly revolving upon itself, then assuming a straight course, or retrograding, 
advancing, or moving sideways, in all directions with equal precision and rapidity ; 
then stopping to pause, and remaining for a time almost immoveable, a slight 
waving of some of its vibrating organs easily counterbalancing the difference 
