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POPULAR SCIENCE REVIEW. 
Of tlie fossil forms, ITytnenocaris was regarded by Salter as 11 the more 
generalized type.” The genera Pdtocaris and Discinocaris characterize the 
lower Silurian period, Ceratiocaris of the upper, Dictyocaris the upper 
Silurian and the lowest Devonian strata, Dithyrocaris and Argas the 
Carboniferous period. Our existing north-eastern species is Nebcdia bipes 
(Fabr.), which occurs from Maine to Greenland. 
The Nebaliad9 were the forerunners of the Decapoda, and form, Dr. 
Packard believes, the type of a distinct order of Crustacea, for which he 
proposes the name of Phyllocarida. 
A Segmental Organ in the Endoproct Bryozoa. — In the Comptes Rendus of 
February 24, 1869, M. L. Joliet brings forward evidence in support of the 
observations of Hatschek, who, in October 1877, indicated in Pedicellina 
echinata , both in the larval and adult state, a vibratile canal, of which, 
however, he did not appear to have well made out the form, and which he 
compared to the vibratile organs of the Rotatoria. M. Joliet states that he is 
now in a position to confirm, correct, and complete the statements of 
Hatschek, and to extend them to the whole group of Endoproct Bryozoa. 
In a spineless variety of Pedicellina echinata which he examined, the 
vibratile organ was double, and situated in the cavity of the body, in the 
space included between the oesophagus, the stomach, and the matrix. It 
consisted of a short tube, ciliated internally, inflated at its middle, which, 
on the one hand, opened into the matrix, not far from its external 
aperture, and, on the other, opened obliquely into the cavity of the body by 
a slightly funnel-shaped passage furnished with active vibratile cilia. This 
organ, furnished with a vibratile pavilion, and placing the cavity of the 
body in communication with the outer world, had all the characters of a 
segmental organ. It appears very early in the bud ; and when the stomach 
is only sketched out, and before the arms are indicated, a ciliary movement 
is already perceptible at the place that it will occupy. 
In a still undescribed species of Pedicellina from the island of St. Paul, 
M. Joliet has also detected the same vibratile organ ; and still later, in the 
Loxosoma of Phascolosoma , he recognized a perfectly similar canal, ter- 
minated by a pavilion and placed in the same situation. As in Pedicellina, 
it appears very early in the bud. 
M. Joliet therefore concludes that in the group Endoprocta, including the 
highest forms of the Bryozoa, the presence of a segmental organ (that is to 
say, an organ which is very generally diffused among the Vermes) may be 
regarded as constant ; and considering the endeavours that have been made 
of late years to approximate the Bryozoa to the Annulata, he thought it an 
advantage to bring this new argument into the debate, as possessing consi- 
derable value. 
