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��or less widciv Chan single pliotographs do under similar conditions. The L-oin|>ositea ought to be almost, wlioHy independent or fortuitous eir- ciimstniicea snchns this; and, nlihnugh the sep- arate negatives of the some individual might exhlljit considerable deviations Horn each oth- er Tor one reason or another, yet such devia- tions shonld iiavc no eumidative cfTect in the cotnijosite, but be in effect obliternted. IT, however, there is. as there well may be, some personal peculiarity in the adjustments of a photographer, his composite will necessarily lie&r the impress of this mannerism, and fur- nish a kind of personal error, which can per- haps be only eliminated by making a composite from a number of composites of the same group, each taken by a different person.
LETTK/iS TO TFfE EDITOR.
A modera type of plant in the cretaceoos.
TnK genua Bmaenice, r>r llydropelUs. \» rep le sun ted in eastern Nnrib America liy n single aperiia, U. pei- laca, Purah (11 yd ropelth purpurea. MIcliauxl, which, according tu Gray, is alsn n native of I'uget Suuitd, Janaii. Auetrnlia, nnd India. A form so widely illi- iribiiied may be eitpected to have been early Intro- diiceil, ill ihat we need not be surprised to find it oraurring along with the earlier tonus uf eioganous lilts In ihf cruiaceous o( our oortb-west.
Theapeolmeiia to which lliis note refers were ob- tained in the beds of the Belly-Ktver series o( the
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��Canadian survey, near Medicine Hal. These beds «re>ipper erelaccou", and h'dd to-alls, some of which resemble those of the Laramie group, nthers those uf Ibe Pierre group. They contain wor liable beds of 11 g- nltlc oal ; and ihe «peclroens in queslinn were found ill nodular clay ironstone, associated wlih one of the coal-beds worked in the ' Liiwsnn mine.'
A specimen of lUla intereslinn fiuuil. obtained. I b^Here, from Mr. Lavrson, the nianngpr of the mine, was kindly giver to tue last year by ilr. J, R. Byron, r>ne of the members of the British association; and HtlditioDal specimens, some of them very perfect, were afterwards cnllecled l)y Mr. T. C. Wesiiin of ihe gei)- losicnl survey. They resemble very closely tlLe leaves
��of the mo(Ji>rn •-pecies, differing only in llicirpenenl smaller size and snmewlrat lt:sa elUptleal form. II slightly in Ihe venation, the primary veins being nd numerous, or aluut eighteen in nu[Dl)er. wLil« ^ teen is a common numl)er in the moderD I
These dlfTerences may indieate merely a i
form; bnt I biive thought It best to designate^ species or variety by Ihe name B. anliigua. Jial^ ated with theae leaves, in thesamebeil, ai-esouieoi aquatics, notably I'isiia corrugata (I.e^'^itx.) and X nasRUiatn (Dii|. both ^peeles of the Lantraie: PlalanU'i nnbllls of Newberry (Aralla iintata of L qucreuvl. which, though nppareuily n-gardeil ia i United Stales as raiocene, is certainly In Cai charactprlsilcally Laramie. There i; also a new cies of Pupuliix — P. tatidenlalK (Un) — clo-ely «]a to the modern P. grandldentala, and an Acer ( A. l katchewense i, whose leaves resemble small or itniL ture leaves of A. dasycarpum. A species of SeqnL also occurs, probably S. Keicheiibachii. Tbouglil these plaiitH have a very modern aspect, tbey a questionably cretaceous; and I have myself at. at the disiniermeni of a dinosaur of the p-iius~l cloiiius from beds overlying those in whicb the l( ' occur. These facts furnlsli another innt
modern aspect of the upper cretaceous fli
I have elsewhere Insisted, and which hits been a ij lUe source of error with reference to itie ace uf t ~ of Ibis formation In the wext. It is iiitrirvaun] note that beds of this age In western CunadM, raxiL the modern Onoclea Kenslbllls of America. aloniEW Davallla tenuifolla, also modern, bnt ii-in> Asiatics J. WM -^
Lateral movementa of the earth'a cmst. I
While observations are being made for the z pose of investigating 'variations of iHtituilc,* la] not desirable that ihe U.S. coast anil ge-iilvtlc ai vey should make simultaneous obwrvatioiis will view to discover, if possible, whether or not ti^^ along our coa&is are suEFering changes of laUlniJsS longitude, or both, due to lateral movements u| ^
If It is true that during geological bisiofy )m lateral movements of the earth's crtm have i-" place, and if snch chanices are still goliiK (^ would seem inevitable, that, In rei;ioii? Mlierw J er.ildisplaepinentsare taking plac". lain I suffer a change of latitude or I.'Hi^lIiii! according to the direction of yielilm:.- ' < < ure, and that places located upon i< — compression or folding thould Im> nu extent, bodily toward places in adj.dniitc reeioi toward which the mnvemeiits take place, but irld are not themsrlves undergoing dlsplncempnta, 3ince verlii'al movemenis of the earth's cm.. . taking place at measurable rates, and since, [n t past, kteral movements appear to have exceeded 2 vertical, it might be exjiecied that lateral e ments are now taking place at measurable i Of course, if the superliclal strata are not Inn.. In these movements, the deeper strata only jlaMifl surface landmarks could not reveal the i but in this case, and in cose folds of the siruta along our coasts are In process of evolu it would seem that tnch changes might b» dlaooi by sinking deep venical shafts at intervale lines norhial to the coast. Thcsie carefully au at intervals during one or two centiirlea. It seem, should >hiiw a measurable warninr - if such movements are going on. F. ]
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