1S6 ROYAL SOCIETY OF CANADA 



Bill.. 0. (H.) ixseulpta, Hall, 0. {Dinorihi&) pectmel/a, Emmons. Para- 

 sti'ojth'ii henUjiliratd, Hall. Ci/closjiiî'a bisulcata. Emmons, sp., (Uitam- 

 boniies dirersa, Shalor, lihynchotrema fna-qiiivaîvis, Castclnau, Zygospira 

 recur nrostra, Hall. 



The L.A.MELLTBRA\CHrATA ai'c not very abundant in our Trenton 

 formation in the Ottawa Valley, but deserve more careful study and 

 attention than has been given to them heretofore. The following are 

 some of the better-known species : — Ambonychia amycjdaUna, Hall, Modi- 

 otopsis (^Endodesma) Gesneri, Bilhngs sp., Goniopjhora cari'mttii. Bill, sp., 

 FroloheUa Trentonensis, Conrad, Ctenodonta gibbosa. Hall, C. levatu, Hall. 

 Of the Pteropoda we have two species of which ConuJaria Trenton- 

 ensis, Hall, is the more alnindant and characteristic. 



The GrASTERopoDA are eminently characteristic, and abound at cer- 

 tain horizons in this formation. Cydonetna Montrealense. Billings, f\ 

 bilix. Hall, abound in the lower Trenton of Hull. (^)ue., whereas Mur- 

 chisonia {Hormotoma) beUicinrta, Hall sp., EccylioptcrusOttaivaënsis, Bill- 

 ings. Sabulites (Fusispira) Jifclutrdsoni, Billings, S. ÇFiisis]dra) subfusi'- 

 formfs, Hall, occur more abundantly in the upper measures of the Trenton. 

 Biuania (Tetranotd) bidorsata, Hall, Biif-ania sulcafina, Emm., Fccu- 

 lioinjduilus Trentonensis, Conrad sp., PJeurotomaria (Liospira) Frogne, 

 Billings, and Trochonenm umbilicaiinn, Hall, are also found everj-wdiere 

 in the Trenton. 



The Cephalopoda include : — OrtJioceras Ottaicaënse, Billings, 0. 

 Xiphias, Bill., 0. Fython, Bill.. 0. rulgatum. B., these are eminently 

 characteristic species of this Ottawa Valle}-, and occur associated with 

 the ubiquitous Camerorwnis /uoteiforme, Hall, and Ortliocenis (tiuplicant- 

 eratum, Hall. 



Vermes are repi'esen ted by ( 'oncJiic/iolitcs Jfcxnosus, lliiW, Serjuilites 

 dissolutas, Billings, and several obscure conodonts abound in a certain 

 band of limestone in Hull. 



TRiLf)jjiTA. From the Ottawa Trenton I)eds was found the first 

 trilobite which showed calcified arches or supports for limbs, and in 18G1 

 Mr. Billings drew the attention of the geological Avorld of that day to 

 the fact. Isotelus gif/as, deKay ( = As((phus pUttycejduiliis, Stokes), is 

 eminently chax'acteristic of the Trenton of the Ottawa Palaeozoic Basin, 

 as elsewhere, and with its contemporary, fatymmene senariK, Conrad, 

 were rivals as far as numbers are concerned. 



Other species of trilobites in the Trenton of the Ottawa Palaeozoic 

 Basin were: — Bronteus lunatus, Billings, Ceniuncs pdeurexanthemvs, 

 Green, Fabnanites Achates, Billings, D. Bebryx, Bill., Fterygomefopus 

 callicephalus, Green, Encrinurus vigilans, Hall, Harpina Ottawaënsis, 

 Bill., H. Deyifoni, Billings, Ulœnus America nus, Billings, I. Milleri, Bill- 

 ings, /. Trentonensis, Emmons, Froëtus parviusculus, Hall, besides 

 numerous Ostracoda which require further study. 



