418 MAZATLAN UNIVALVES 
Of this broad and strongly built species, three young shells, 
one adolescent and one adult were found. It is known at once 
from Chr. ovata by the prominent little vertex at the head of 
the pointed spire. The first whirls are very spreading. The 
base is angulated in the adolescent shell, but rounded in the 
adult. The base of the columella is produced in all stages, 
almost notched when young. The labrum is extremely thick 
in the broken shell. The sutural groove is formed as in Chr. 
telescopium, but the sculpture: most resembles that of Chr. 
ovata. A young specimen with two and a half normal whirlg 
measures long. °046, long: spir. *022, lat. °034, div.*50°. 
The adult sp. oie el 6a9e P 5098) a. oi Of2. oan aces 
Hab.—Mazatlan ; 5 sp. off Spondylus ; L’pool Col. 
Tablet 1969 contains the adult and a young specimen. 
505. CHRYSALLIDA ROTUNDATA, 2. S. 
Chr. t. tenuiore, ovatd, solidd ; vertice nucleoso parvo, planato, 
verticaliter in medio site, prominente, marginibus spire excur- 
vatis parum superante ; anfr. iv. normalibus, tumentibus, - 
suturis conspicuis liris xi. spiralibus, solidis, rotundatis, con- 
tiguis, quarum Vv. in spird site sunt ; interdum, maxime i testa 
juniore, transversim tuberculosis ; tnterstitiis tenue decussatis ; 
basi rotundatd; apertura paren contracta, periiremati continuo, 
labio tenui, plica obtusa, vix celatd. 
Of the shape of Chr. ovata, but even more like the normal 
Odostomiz; with a very different vertex ; and separated from 
all the other species by the transverse markings being almost 
obsolete. They appear however here and there, as though to 
shew the bond of relation. In this species also the young 
follows the type of the adult. Nine complete shells and a few 
fragments were found. Long. °09, long. spir. °048, lat. *045, 
div. 35°. 
Hab.—Mazatlan ; very rare, off Spondylus; L’pool Col. 
Tablet 1970 contains the youngest, the largest and an inter- 
mediate specimen. 
506. CHRYSALLIDA OBLONGA, %. S. 
Chr. testa ovato-oblongd, tenuiore, alba; vertice nucleoso ut 
in “Chr. rotundaté ;” anfr. v. normalibus, subconvexis, suturd 
distinctd ; liris v. in spird spiralibus, rotundatis, interstitis 
