250 MAZATLAN UNIVALVES 
Genus GLOBULUS, Schum. 
Schumacher, Essai Sc. 1817, no, 23 : (non Sow.).—Phil. Handb. 
Conch. p. 208. 
Rotella, Lam. 1822, et auct. 
Umbonium, Link; A. Ad. Mon. in Proc. Zool. Soe. 1853, 
pmss:—H. dA. Ad. Gen. vol: 1. 'p. 407. 
Pitonellus, Montf: 
Helicina, (Zam. & prima manu) Gray in Proce. Zool. Soc. 
1847, p. 145. 
e 
317. PGLOBULUS TUMENS, 7. s. 
2G. t. globosd, solidiusculd, alba, subnitente ; spird planata, 
depressa, anfractibus iv. suturad haud impressé ; striulis spira- 
3 > 
libus subobsoletis tenuissime ornata ; callositate valde tumente, 
trientem partem basis tegente, suturad impressa, umbilicum 
i ’ ‘Pp ) 
tegente, in parietem et intus suturam spiralem ascendente, juxta 
bi } anatum ; apertura intus rotundatd, labro i 
labium vix planatum ; apertui ; 
spiram ascendente. 
This species is intermediate between the typical Globuli and 
the Ethalie. In the faint sculpture and slight planing off of 
the callosity, it presents the characters of the latter genus ; 
in the large swelling growth of the callus, which appears glossy 
over the whole surface, and covers the body whirl within the 
mouth, running up to the suture, it is a true Globulus. Two 
older specimens were found, sufficiently agreeing in other 
respects, but displaying a groove in the callus near the base of 
the columella, exactly in the same place, which is remarkable 
if accidental. They are both however worn specimens. If it 
should prove a constant character, they may take the name - 
of “G. sulcatus, ¢. callo basim versus subprofunde sulcato.” 
Long. 018, lat. 038 by °033, div. 160°. 
Hah.—Mazatlan ; 3 sp. off Chama and Spondylus; Z’pool Col. 
‘Tablet 1168 contains the fresh specimen, and one of the form 
G. sulcatus. 
Sopcenus ETHALIA, -H. & A. Ad. 
Gen. vol. 1. p. 409 :—Proc. Zool. Soc. 1853 (Mon. Unb.) p. 189. ° 
A small group of Mazatlan shells, of the general aspect of 
Vitrinelle, and agreeing with Globulus in having a callous base, 
