Miscellaneous Notices. 459 
also much variation. When once these specific though varia- 
able forms appear they lived till the variations which could 
be played on them were exhausted; and the species ceased to 
live and sont extinct either near the close of the Carbonif- 
erous or not till later in the Mesozoic. 
Some of the races or varieties may die out but they peeb ben 
again and again till there are such strong contrasts that i 
difficult to see even generic can orig between them 
The following is a tabular view of the Satiing of the 
Silurian and Devonian forms of which Spirdfer oe of the 
Niagara in New York. is the type; the tracing of the history 
through the European forms and higher into the Carboniferous 
is reserved for further study. In the table, lateral extension is 
expressive of the morphological variations; each line repre- 
sents one of the geological puna which are aun ae in 
their natural order; and the name of each species is place 
the position on the line representing its supposed relation to 
the typical form of Sp. cris 
Chemung prematurus 
Porta eevis 
Hamilton oo ee fimbriatus_-_-.-- -. subumbona 
Corniferous fimbriatus 
Orisk tribulis 
N.Y. & Tenn. .. Saffordi (pars. ) agoas 
Maryland ..-~-octocostatus __..modestus 
Lower ea Woe Fick cyclopterus rus (pars fates 
New York anuxemi 
: abnle ) <) +7864 aa) ies seee eal eee et = ObspUus sy. -.<5-. 
Naw Time caraakcue ..--fuleatus (pars.).. 2... Chspusacct.. bicostatus -.-.-- 
A History of the Jetties at the Mouth of the ras River, by E. L gh 
thell, C. E., Chief Assistant and Resident Engineer during their constru 
384 pp. 8vo. Illustrated by numerous maps and geome and with a portale of 
Mr. J. B. Eads as its frontispiece. New York. (J. Wiley & Sons 
Réutgen’s Principles of rhaiene taeda with special applications to hot-air, 
t e 8. ised A. Jay DuBois. 
: befo 
field, in August, 1879, aiming to show especially that the Ascidians are 
brates. 
History of North American Pinnipeds: a oe es of the Walruses, Sea- 
saph Allen, Assist. Mus. 
lions, Sea-bears and Seals of North America: by Joel A 
omp. Zool. Cambridge. 786 pp. 8vo. With a number of wood cuts. 1880. 
Constitutes N ° oe" = ea emertoor Publications” of the U. 8. Geolc gical 
nd Geographical Survey of t rritories under en, Geologist-in- 
Su 
ol er. 
cal, Srymetinrs and Economical, and as 
interesting to the garter Spor as it is valuable to science. 
Second Treatise on the decrease of Water in Bariage Creeks and Rivers, 
co 
Sir Dip rowed Wex, Chief Siainves of ne ce eats of the Danube, at 
he papers of the Society of the an Engineers and Architects, ee 
ig 6-8, translated by G. Weitzel, Major ingiiaers Brevet Maj. Gen. U. 8. A 
