90 
Tubicola 
Serpvla sodalis Goldfuss 
Pelecypoda 
Ctenostreon gikskanensis n. sp. 
Lima tizglmsis n. sp. 
Oxyioma submcconnelli n. sp. 
Ostrea weegeti n. sp. 
Pema weelaupensis n. sp. 
Plagiostoma hazeltonense n. sp. 
Trigonia guhsani n. sp. 
Ammonoidea 
Sonninia hansoni n. sp. 
Sonninites &ilveria n. sp. 
Sonninites skawaki n. sp. 
Guhsania betta n. sp. 
Guhsania ramata n. sp. 
Other pelecypods, a few brachiopods, and rare gastropods are also present* 
Among the pelecypods, the presence of a Trigonia of the costatce 
section, of a Ctenostreon resembling Ct. pecteniformis (Schlotheim) and 
Ct. electra d’Orbigny, and of a Plagiostoma near P. giganteum Sowerby 
indicates a Jurassic age; as does also the presence of the annelid Serpula 
sodalis Goldfuss. The ammonites admit of a finer correlation. A very 
detailed chronology of the English and continental Jurassic has been built 
up by S. S. Buckman , 1 based on the succession of ammonites. It embraces 
about forty-three ages and each age includes a variable number of hemerae. 
Each age or hemera expresses an interval of time, the duration of certain 
species and genera. Now in this chronology the date of the Sonninia is the 
sauzei hemera of the Sonninian age; the date of the Sonninites is the 
alsaticus hemera of the Sonninian age; the new genus Guhsania is related 
and parellel in development to the liostraca group of the genus Dorsetensia, 
the date of which is the Epalzites hemera of the Stepheoceratan age. The 
affinities of the Silver Lake fauna, or faunas, therefore, are with those 
English faunas that date from the sauzei to the Epalxites hemera, or from 
late Sonninian to early Stepheoceratan. Faunas of the Sonninian and 
Stepheoceratan ages range throughout the Middle Inferior Oolite or 
Bajocian strata of England. Therefore, the fossiliferous beds of the middle 
sedimentary division of the Hazelton group, on Hudson Bay mountain, 
are to be correlated with the middle of the Middle Inferior Oolite or 
middle Bajocian or early Middle Jurassic strata of England. 
English strata 
English ages 
English hemerse 
Middle Inferior Oolite 
Stepheoceratan 
Epalxites 
pardcarimta 
Masckeites 
Range of Silver 
Lake ammonites 
Sonninian 
alsaticus 
propinquans 
sauzei 
i "Type Ammonites”, vol. IV, pp. 6-18, 48-49; vol. V, pp. 71-78. 
