oa 
580 The American Naturalist. [July, 
in only one case can two species be referred to one genus, In the Ful- 
goridae each of the three species belongs to a different subfamily. 
Another striking feature of the fauna is the size of the individuals 
which compose it. The majority of them represent the most bulky 
species of their respective families. The average length of these 
Cenozoic species of Fulgoridae and Cercopidae is not less than two 
centimeters, and there are some that are double that length. 
The author states that this insect fauna indicates that the deposits in 
which they occur are at least as old as Oligocene, but no definite state- 
ment as to the age of the beds can be made. 
A third interesting paper in this series on Canadian fossil insects 
sums up the present knowledge of the Coleopterous remains of Canada. 
These have been found in seven distinct localities in that country, and 
at three very different horizons. The greatest interest attaches to the 
collection made at an interglacial locality near Scarboro’ Ont., which 
yielded twenty-nine species, and is the largest assemblage of insects ever 
found in such a deposit anywhere. Forty-five species from the various 
localities are described by Mr. Seudder. They are referred to 27 
genera, 2 of which are new. (Contrib. Canadian Paleontol., Vol. II, 
Pt. I.) 
Jackson on the Development of Oligoporus.—The fol- 
lowing is an abstract of the results of the recent studies of the Palæoe- 
chinoidea. In Oligoporus the interambulacra terminate ventrally in 
two plates, which present on their oral faces a reéntrant angle for the 
reception of a single initial plate of the area. Proceeding dorsally, 
new plates and new columns of plates are added, accenting by their 
appearance stages in growth, as he had previously shown in Melonites, 
until the full compliment of the species is attained. The single initial 
interambulacral plate of Oligoporus was compared with a similar plate 
in Melonites, Lepidechinus, young modern Cidaris, etc. At the ventral 
or younger portion of the corona of Oligoporus there are only two 
columns of ambulacral plates. The four columns characteristic of the 
adult are derived from these two by a drawing-out process. The four 
columns of ambulacral plates of adult Oligoporus are the equivalent 
of the two outer and two median columns of Melonites. These four 
columns in both genera are the morphological equivalent of the two 
columns seen in the ambulacra of Bothriocidaris, Cidaris, ete. a 
Oligoporus, as shown by the development of both ambulacral alla 
interambulacral areas, is a genus intermediate between Palsechinus 
and Melonites. During the nother of a it. — 
eae ee Oe 
