356 (Review of (Recent Geological Literature. 
of a small proportion of sand grains cemented together bj a mixture of 
phosphate and carbonate of lime (a condition best shown in the third 
group of specimens above mentioned) is shown by good reasoning to be 
erroneous; while Carter's view, that the skeleton may have been origin- 
ally chitinous in nature, is likewise thrown aside to give place to his own 
view. This is, that the skeleton of Parkeria, like that of the Sirotnafop- 
oroids, "was originally composed of carbonate of lime, and that phos- 
phatization, when it has occurred at all, has been the result of secondary 
processes which have operated subsequently to fossilization." 
The author next works out the minute structure of the organism in a 
very satisfactory manner, showing by good illustrations, that the radial 
pillars and the connecting concentric lamellae are composed of innumer- 
able, minute, simple, untabulated, cylindrical or polygonal tubuli, having 
a radial disposition. These tubvili are separated by thin, porous walls, 
allowing free communication between their cavities. The general can- 
cellated tissue formed by them is regarded as ccenosarcal in its origin, 
and compared with the canaliculated ccenosarcal tissue of Dtsttckofora, 
AUopora, Pliobotkriis., etc., and with the clathrate tissue of the Hydrac- 
tiniidae. 
A coarser kind of cancellated tissue it commonly developed in thin 
concentric bands at periodic intervals, separating thick strata of the 
ordinary skeletal tissue. It consists of wide, irregular cells or tubuli, 
united by coarse reticulated tissue. This the author is disposed to re- 
gard as representing a periodic development of reproductive zooids, and 
to compare with the periodic production of "ampulla;" in the Stylasterids. 
Certain more or less numerous, large, oval or circular tubes, averaging 
0.15 mm. in diameter, are svipposed to have contained zooids, and to cor- 
respond to the gastropores and dactylopores of the Hydrocorallines. 
Lastly the author compares the form under discussion with some re- 
cent and many extinct organisms, showing its relations to the Stromato- 
foroidsy the curious Mitcheldcania., Syringosfhcpra, and other forms. 
With regard to the systematic position of Parkeria., he concludes that 
"there can be little hesitation in accepting Mr. Carter's reference of the 
genus to the Hydrozoa. All the known facts as to the chemical consti- 
tution, mode of growth, and general structure of the ccenosteum, no less 
than the minute structure of the skeleton-fibre, point unequivocally in 
this direction. With regard to the precise place which Parkeria should 
occupy in the series of the Hydrozoa, it may be regarded as intermediate 
between the Hydrocorallines and the Hydractiniidae, but with nearer re- 
lationships to the latter than to the former. In the minute structure of 
the skeletal tissue Parkeria most closely resembles the Hydrocorallines; 
but in the general arrangement of its parts, and more particularly in its 
mode of growth by the production of successive concentric lamella" sep- 
arated by rows of chamberlets, it approaches most nearly to the Hydrac- 
tiniidse, with which group the genus may in the meanwhile be ranked." 
A brief narrative of the Journeys of David TJiompson. By J. B. Tyrrell, 
of the geological survey of Canada (Proc. of the Can. Inst., March, 1SS8). 
