MAZATLAN UNIVALVES 417 
Section A. Species Odostomoidee. 
503. CHRYSALLIDA OVATA, 2. S. 
Chr. t. haud parva, solidd, ovata, alba; vertice nucleoso 
parvo, omnino celato ; marginibus spire parum excurvatis ; 
anfr., paucioribus quoad maygnitudinem, iv. et dimidio, subro- 
tundatis ; suturd impressd ; liris tuberculosis transversis, testé 
juniore subdistantibus, testa adulté contiguis, marginibus spire 
wa parallelis ; lirulis spiralibus, in spird iw. vix monstrantibus, 
circa peripheriam et basin rotundatas, vl. validis, rotundatis, 
interstitiis parvis rugoso-decussatis ; apertura parwn contracta, 
peritremati continuo, labio interdum rimulam umbilicalem 
monstrante ; plicd solidd, obtusa, parwm celatd. 
This species and the next are at the confines of the group, 
with which they agree in general habit, sculpture, and con- 
tinuous peritreme, while the form is that of the typical Odos- 
tomie. The pattern closely resembles that of Chr. nodosa, 
and the apex that of Chr. fasciata, from both of which it differs 
in its broad expanding form, the adolescent shells being like 
the adults. The lip is not thin, but agrees with the group in 
being much more solid within, as is shewn by the broken 
shells, of which there were several, though very few of any age 
were perfect. The largest (a monster for the group) measures 
long. °155, long. spir. ‘08, lat. ‘083, div. 35°. 
Hab.—Mazatlan ; very rare, off Spondylus; Z’pool Col. 
Tablet 1968 contains the youngest, the oldest, and an inter. 
mediate specimen. 
504. CHRYSALLIDA NODOSA, 2. s. 
Chr. t. subconicd, solidd, alba ; vertice nucleoso minimo, 
prominente, marginibus spire via excurvatis parum superante ; 
anfr. normalibus v. latis, subplanatis ; lirulis spiralibus iv. 
transversis usque ad xvi. sibi parallelis, ad intersectiones nodosis ; 
tuberculis rotundatis, validis, transversim attingentibus, spirali- 
ter plerumque separatis; lirulis transversis supra suturam 
impressam declivibus ; lirulis spiralibus in basi rotundaté 
vi. rotundatis, interstitiis tenue decussatis; plicd columellart 
parum celata, valida, obtusd ; aperturd (in t. adultd) oblonga, 
parum contractd, ad basin product, peritremati continuo, labia 
haud tenui. 
