34 
MUSEUM BULLETIN NO. 3. 
Family, Meristellidae Hall and Clarke. 
Hyattidina charletona new species. 
(Plate I, figures 6-7.) 
The single specimen upon which this species is based was dis- 
covered on a slab from Charleton point, the same slab con- 
taining Phragmolites pannosa } Zygospira recurvirostra n. var., 
and other Richmond fossils. Had it occurred in higher strata 
no hesitancy would have been felt in referring it to H . congesta 
junea , although it is somewhat smaller, proportionately longer, 
and has a small longitudinal groove on the dorsal fold which 
is not present in that species. The general shape is elongate 
ovate, the posterior outline being trigonal, the anterior two- 
thirds elliptical. The apical angle is about 110 degrees. Both 
valves are convex, the ventral slightly the more. The beak 
of the ventral valve is small, narrow, pointed at the apex, be- 
neath which is a small foramen. A medium ridge, grooved 
toward the front, extends from the umbo to the anterior margin. 
From the depression bounding this ridge the surface slopes to 
the lateral margins. The dorsal valve is marked by three convex 
lobes of which the middle widens towards the margin and be- 
comes divided by a longitudinal groove. No area has been 
seen on either valve. The shell is 4 mm. long, 3.5 mm. wide 
about mid length, and 1.25 mm. thick just in front of the umbo. 
No hesitation is felt in referring this little shell to the genus 
Hyattidina though the interior has not been seen. This genus 
has hitherto in America not been found below the Clinton, but 
in England Rhynchonella? porllockiana Davidson [demonstrated 
by Reed to belong to the genus Hyattidina (Reed, Quar. Jour. 
Geol. Soc., 1897, p. 75)] ranges from the upper Llandeilo to the 
Bala; hence its appearance in American strata as early as the 
Richmond should occasion no surprise. It is further probable 
that H. charleton is a migrant from the British seas and is in 
the direct line of ancestry to H . congesta , since it chiefly differs 
from H. portlockiana in having the lateral slopes near the car- 
dinal angles concave instead of convex, and Reed states that 
the latter differs from H. congesta only in the “presence of a 
short median septum in the brachial valve, and in the greater 
length of the process of the loop.” 
