Notes on the Genus Quenstedtia. By Joun Lycerr, Esq. 
Reap 16ru SerremBeR 1856. 
Turs genus of Lamellibranchiate Conchifera, described in the 
Great Oolite Monograph of the Palzontographical Society, was 
founded upon two shells figured in Prof. Phillips’s ‘ Geology 
of Yorkshire,’ under the names of Pullastra oblita and Psam- 
mobia levigata, the former of them being chosen as the type of 
the genus. 
Of Pullastra oblita, I have succeeded in clearing and exposing 
the hinge of each of the valves in many instances, and am per- 
fectly conversant with its characters, which will be found correctly 
described in the Monograph alluded to. The siphonal, pallial 
and muscular scars were ascertained in a cast from the York- 
shire Dogger, and upon the characters supplied by these satis- 
factory materials the genus was founded. Specimens with the 
test preserved, and which admit of the hinge characters being 
. exposed, are obtained in the upper portion of the Inferior Oolite 
of the Cotteswolds; a single young example of the species only 
having been afforded by the Great Oolite of Minchinhampton. 
In the Great Oolite Monograph it was stated to be allied to 
Psammobia, but distinguished from it by the dental characters of 
the hinge, and by the absence of an elevated nymphal plate to 
sustain the ligament. The general resemblance which the aspect 
of this shell presents to the Mactromya mactroides of Agassiz 
had not been overlooked, but as the figures of Mactromya mac- 
troides, in the ‘ Etudes critiques’ of that author, consist for the 
most part only of casts, which afford no information respecting 
the hinge, it was considered unadvisable to allude to the pro- 
_ bable identity, as it was certain that Quenstedtia possessed no 
affinity either with Mactra or with the family of the Myade, and 
the shells of Phillips had priority as species. This supposed 
identity of Quenstedtia oblita with the Mactromya mactroides of 
Agassiz, has recently been fully confirmed in the publication by 
M. Terquem of an elaborate work, with plates, entitled, ‘ Obser- 
vations sur les Etudes critiques des Mollusques fossiles, com- 
prenant la Monographie des Myaires de M. Agassiz.’ In this 
work the author has figured and described the Mactromya mac- 
