424, MAZATLAN UNIVALVES 
sometimes not more than two and a half in the adult. <A 
Pvariety has the sculpture much finer. A large sp. measures 
long. °055, long. spir. 032, lat. 027, div. 25°. 
Hab.—Mazatlan; not common, off Spondylus and Chama; 
DTP pool Col. 
Tablet 1982 contains 9 specimens in different stages. 
Section C. Species Chemnitziformes. 
513. CurysaLuipa @natHrRatouna, C. B. Ad. 
Chemnitzia clathratula, C. B. Ad. Pan. Shells, p. 165, 311, 
no. 222. 
This species passes into the rounded cancellated forms of 
Chemnitzia, (Subgenus Dunkeria.) from which it is known by 
the distinct fold on the columella. and continuous peritreme. 
The last whirl is but shghtly contracted. It is known at 
once from the rest of the Chrysallide by its very elongated 
form and rounded whirls. The solitary Mazatlan specimen has © 
lost its upper portion; but the imperfection of the aperture 
brings to light the oblique distinct columellar plait, which 
escaped the notice of Prof. Adams. 
Hab.—Panama; 10 sp. ip sand; C. B. Adams.—Mazatlan ; 
1 sp. off Chama; L’pool Col. 
Tablet 1983 contains the specimen. 
514. CHRYSALLIDA CONVEXA, 7%. S. 
Chr. t. gracili, tereti, tenui, albidd ; vertice nucleoso anfr. ii. 
helicoidalibus, magnis, declivibus, marginibus spire, parum 
excurvatis, superantibus, quarum apex in anfr. normali prima 
horizontaliter jacet, parum prominens ; anfr. normalibus v. valde 
‘ convexis, liris obtusts circiter xiv. radiantibus, ad suturam pro- 
fundam sepius attingentibus, circa basin evanescentibus ; lirulis 
spiralibus in partem anteriorem anfractuum, interstitia tenue 
decussantibus,, quarum ill. in spird videntur, circa basin satis 
rotundatam plures ; apertura subovali, parum contracta ; 
columella oblique plicatd ; labio tenut. 
This remarkable shell has the apex and growth of a Chem- 
nitzia, the convex whirls: of Aclis, with the spiral plait and 
(slightly contracted) aperture of Chrysailida. The lower half 
