236 MOLLUSCA; 
spire, the more yellowish hue of the white colour, the subangular last whorl, and the 
very slight turning out of the apertural margin ; this last-mentioned character proves 
it to be adult, although the shell has one whorl less than that of O. livescens. The 
stripes are pale brown, disposed at unequal intervals, and very variable ; they are seen 
chiefly on the whorl before the last, sometimes also on the last, while on the other 
whorls spiral rows of spots, or even bands, also pale, however, predominate. (On 
account of some of the whorls being differently painted to the others, Dr. Pfeiffer 
seems to have used the name “ heterogeneus,” which at first leads one to suppose that 
the species possesses much more peculiar and unusual characters. 
49. Otostomus semipellucidus. (Tab. XV. fig. 10.) | 
Bulimus semipellucidus, Tristram, P. Z. 8. 1861, p. 230, t. 26. fig. 8°; Pfr. Monogr. Helic. Vivent. 
vi. p. 22”. 
Bulimulus (Liostracus) semipellucidus, Fisch. & Crosse, Miss. Scient. Mex., Mollusca, i. p. 507°. 
Hab. Gouatemata (Salvin'~*). 
N.W. Costa Rica: Guanacasta, in the Bay of Salinas (Péctier). 
N.E. Costa Rica: Puerto Viejo, on the Rio Sarapiqui (Biolley). 
CentRAL Costa Rica: Alajuela (Orosco). 
I am rather inclined to think that this is an albino variety of O. discrepans. 
The specimen from Guanacasta, from which our figure is taken, has a few brownish 
oblique stripes on the whorl before the last, whereas in all other respects it agrees with 
the Rev. H. B. Tristram’s description and figure; but as the whorls are a little more 
convex than in 0. discrepans, and the umbilical cleft completely closed, I dare not 
assert it positively. Tristram’s figure! is somewhat magnified, as is proved by his 
statement in the text, that the length of the shell is 18 millim. He gives the breadth 
as 8 millim.; but this is too narrow, as by reducing the measurements of his figure 
we find 94 millim. as the breadth of the last whorl. Probably he has, judging from 
the example of Dr. Pfeiffer, measured the breadth just above the upper edge of the 
aperture, which is in reality the breadth of the penultimate whorl. This must be kept 
in mind when comparing my measurements with those given by Dr. Pfeiffer. 
The Costa Rica specimens have stripes only on the upper whorls and also here less 
numerous than in the type. Fischer and Crosse reproduce the original description ! 
and add Duefias as a locality. No dependence, however, can be placed upon this 
statement, as many of Mr. Salvin’s shells were obtained in the vicinity of Coban, 
Vera Paz. 
50. Otostomus panamensis. 
Bulinus panamensis, Broderip, P. Z. 8. 1833, p. 105°; Sowerby, Conch. Illustr., Bulinus, fig. 25 *. 
Bulimus panamensis, Deshayes, in Lamarck’s Hist. Nat. des Anim. sans Vert. ed. 2, viii. p. 273°; 
Pfr. Monogr. Helic. Vivent. ii. p. 206%; Reeve, Conch. Icon. v., Bulimus, t. 18. fig. 70°. 
