1889 .] 
323 
[Foerste. 
The relative length of a specimen increases with age. A speci- 
men 14.5 mm. long has a length equal to .85 the width ; 20 mm. 
long, a length equal to .83 the width ; 26 mm. long, a length equal 
to .81 the width ; 52 mm. long, a length equal to .78 the width. A 
characteristic feature of this form is the slight difference between 
the elevation of the dorsal and ventral beak. It is here placed as 
a variety under S. lens. 
Stricklandinia triplesiana , Foerste, is another species, closely re- 
lated to variety Saltern. Figure 14, of Plate xiv, Bull. Denison 
Univ. Lab., is very similar to forms of the Anticosti variety at 
hand, except in length and the slight anterior extension of the mar- 
gin at the mesial fold, which is less pronounced in variety Salterii. 
It is 28 mm. long and 30 mm. broad. Fig. 13 of the same plate 
is more like S. melissa, Billings, in the character of the postero- 
lateral angles, but otherwise closely resembles the other specimen. 
This is placed as a variety under S. lens. 
Stricklandinia Melissa , Billings, is another Anticosti form known 
only from the description of a single specimen. Like figure 13 of 
the plate just cited the postero-lateral angles at first form almost 
a right angle, after Which the lateral margins diverge to about 
mid-length, after which they curve inwards and around the anterior 
margin of the shell, the curvature being regular except at the an- 
terior margin which is somewhat pointed, but very obtusely. This 
form again seems to have been quite convex along the cardinal mar- 
gin. There does not seem to have been a mesial fold or sinus ; 
these however are sometimes obsolete in the forms already described. 
The length of the shell is about 42 mm., the width apparently 40 
mm., the length of thecardinal line27 mm., and the thickness about 
14 mm. These measurements are taken from the published figure. 
This form is also placed as a variety under S. lens. 
At Collinsville, Alabama, numerous casts of a form occur pre- 
senting all the features of the interior of S. lens in the typical 
European forms. The character of the outline of the shell varies. 
In one specimen the square postero-lateral angles with divergent 
lateral sides* and other features of var. melissa are well shown, but 
these valves are all either flat or very moderately convex ; indeed 
they are all so flat as to lead to the idea that this flattening was 
due to causes subsequent to death since there is scarcely any room 
for the viscera. In other specimens the cardinal line is scarcely 
shorter than the width of the shell, in younger specimens at least, 
