NATURAL SCIENCES OF PHILADELPHIA. 915 
the suppression of the inner, lower lateral angle of the base of 
attachment and inner side cutting point. Marginals (0) low, 
wide, the reflection broad, equalling the base of attachment and 
bearing one inner, broad, long, oblique, bifid cutting point, the 
inner division the smaller, and two outer, smaller, stout, sharp, 
side cutting points. 
Subgenus AGLAJA. 
Jaw thick, high, arched, ends but little attenuated, blunt; cutting 
edge without median projection ; anterior surface with stout, sepa- 
rated ribs, denticulating either margin, from 5 to 9 
in H. infumata (fig. 58), about 6 in jfidelis. The 
other American species, 7. Hillebrandi, I have not 
examined. 
Lingual membrane long and narrow. That of 
TEN OE Hillebrandi not examined, those of infumata and 
Helixinfumata. Z ‘ , ; 
fidelis agreeing in their general characters. The 
centrals have a base of attachment longer than wide, with incurved 
lower margin and expanded lower lateral angles; upper margin 
broadly reflected; reflection short, stout, with no side cusps or 
cutting points, but a very stout, short median cusp, bearing a 
short cutting point. Laterals like the centrals, but unsymmetri- 
cal by the base of attachment wanting the inner, lower lateral 
expansion ; it is, however, unusually developed on its inner side 
margin: first marginals (6 of each figure) differing from the late- 
rals by the equalling of the reflection and base of attachment, the 
lesser development of the cusp, and greater development of the 
cutting point, which is bluntly bifid, the inner division the smaller. 
On some of the first marginals of infwmata (pl. XIII., fig. 9, b) 
there is a small side cutting point. Marginals low, wide, the re- 
flection equalling the base of attachment, and bearing one long, 
oblique, wide, bifid cutting point, the inner division the smaller, _ 
and one or two short, sharp, side cutting points. There is great 
variation in the cutting points. 
A comparison of the two figures will show a longer base of at- 
tachment in fidelis, with a line of reenforcement or duplication to 
its upper margin. As with all species, there is much variation in 
the length of the cutting point, in centrals and laterals, and their 
arrangement and development in the marginals. 
