CYCLOPHORUS. 
Puate XVI. 
Species 71. (Mus. Cuming.) 
CYCLOPHORUS ALTERNANS. Cycl. testd modicé profunde 
umbilicatd, orbiculari-depressd, tenuiculd, sub epider- 
mide pallidée fuscescente decidud pellucido-albd, versus 
apicem pallidé rosaced ; anfractibus angustis, ad su- 
turas lineari-impressis, deinde rotundatis, undique 
spiraliter acuté multiliratis, liris superis lird minore 
interveniente ; apertura circulari, labro simplici. 
THE ALTERNATING CycLopHorus. Shell moderately 
deeply umbilicated, orbicularly depressed, rather 
thin, transparent white, tinged towards the apex with 
rose, beneath a deciduous pale-brown epidermis ; 
whorls narrow, linearly impressed at the sutures, 
then rounded, everywhere spirally sharply many- 
ridged, upper ridges with a smaller alternate ridge 
running between them ; aperture circular, lip simple. 
Cyclostoma alternans, Pfeiffer, Pro. Zool. Soe. 1851, 
p. 249. 
Cyclophorus alternans, Pfeiffer. 
Hab. Madagascar. 
A light transparent shell, corded in a marked manner | 
throughout with sharp ridges, between the upper of which 
there is a fine intervening ridge. 
Species 72. (Fig. a, 6, Mus. Cuming.) 
CycLtopHorus Forprsianus. Cycl. testd modicé per- 
spective umbilicatd, orbiculari-depressa, pellucido-ru- 
bella vel albidd, versus apicem rubella ; anfractibus an- 
gustis, liris spiralibus inequalibus densé exsculptis, 
juxta suturas impressis, deinde rotundatis ; apertura 
oblique circulari, labro simplict. 
Forses’ CyctopHorts. Shell moderately perspectively 
umbilicated, orbicularly depressed, transparent red, 
or white, reddish towards the apex; whorls narrow, 
densely sculptured with unequal spiral ridges, im- 
pressed next the sutures, then rounded; aperture 
obliquely circular, lip simple. 
PruirFrer, Pro. Zool. Soc. 1855, p. 104. 
Hab. New Hebrides, Macgillivray. 
Though bearing a strong general resemblance to the 
preceding species, C. Forbesianus is of a different form, 
more perspectively umbilicated, while the sculpture is un- 
equal, less regularly defined. 
Species 73. (Fig. a, 4, Mus. Cuming.) 
CycLopnorus Mextcanus. Cycl. testd subpatenté per- 
spective umbilicatd, orbiculari-depressd, carneo-albida 
vel aurantio-rubelld ; anfractibus subangustis, dense 
transversim striatis, jueta suturas anguste depresso- 
planis, deinde rotundatis, ultimo prope aperturam laxe 
convoluto, producto ; apertura circulari, labro reflexo, 
jucta wmbilicum profundé emarginato, intus vivide 
aurantio-riufo. 
Tue Mexican Cyctopuorvs. Shell rather openly per- 
spectively umbilicated, orbicularly depressed, flesh- 
white or orange-red; whorls rather narrow, densely 
transversely striated, narrowly depressly flattened 
next the sutures, then rounded, last whorl loosely con- 
voluted and produced near the aperture; aperture 
circular, lip reflected, deeply notched next the umbi- 
licus, bright orange-red within. 
Cyciostoma Mexicanum, Menke, Synopsis, p. 133. 
Aperostoma Mexicanum, Pfeiffer. 
Cyclotus Mexicanus, Gray. 
Cyclophorus Mexicanus, Pfeiffer. 
Cyrtotoma Mewxicanum, Morch. 
Hab. Vera Cruz, Mexico. 
In C. Mewicanus the last whorl loses its sutural hold on 
the penultimate whorl on approaching maturity, and a 
broad notch is formed in the lip, near to the umbilicus, 
resembling the usual gap caused by divided margins. An 
interesting law in the economy of the animal is here repre- 
sented. The margins of an aperture necessarily become 
divided where there is an intervention of the preceding 
whorl. In @. Mewicanus the aperture is loosed from the 
preceding whorl, but yet the margins are divided for its 
reception. 
Species 74. (Fig. a, 6, Mus. Cuming.) 
CycLopHorus BowurcieRt. 
catd, orbiculari-depressd, ustulato-olivaced ; anfracti- 
Cycl. testdé ampliter umbili- 
bus angustis, versus apicem spiraliter tenué liratis, liris 
gradatim evanidis, anfractu ultimo circa umbilicum 
transversim corrugato ; aperturaé oblique circulari, 
labro simplici. 
Bourcizr’s CycLopuorts. Shell largely umbilicated, 
orbicularly depressed, burnt-olive; whorls narrow, 
spirally finely ridged towards the apex, ridges gra- 
August, 1861. 
