358 MOSTLY MAMMALS 
mediate between the long and the short types. As already 
said, these cowries have the central area of the back reticu- 
lated or white-spotted, and lighter than the black-spotted 
margin. And from such a type the transition is easy to 
the modification presented by the serpent’s-head cowry 
and the Surinam-toad cowry, in which the central area is 
white or chestnut-spotted, while the margin and much of the 
under-surface is dark brown. The great width and short- 
ness of these cowries afford further evidence of their high 
degree of modification. Obviously the chestnut-bordered 
cowry is another member of this group in which chestnut 
spots have been superadded to the normal white-spotted 
central area. Apparently a special development of this type 
may be recognised in the white ring-cowry (C. annulus), 
the yellow ring from which it takes its name marking the 
line of division between the original spotted central area 
and the dark area, Finally, from the ring-cowry may easily 
be derived the money cowry, in which the ring has all but 
disappeared, while the marginal area has developed a series 
of rugosities, apparently connected with the filaments on 
the margins of the mantle-lobes, which scarcely intrude on 
the central area. Whether these two white species have a 
habitat different from that of their brethren is a subject well 
worth the investigation of those who have the opportunity. 
Omitting mention of certain other sub-types, this part of the 
subject may be concluded by brief reference to the true Argus 
cowry (C. argus), which, from its elongated form and the 
retention of barring, is evidently an ancient type specially 
distinguished by the ring-like form of the spots. 
All the above-mentioned species (together with a host 
of others) are members of the typical genus Cypraea, 
distinguished by the smooth and shining enamel, and the 
circumstance that the teeth of the mouth do not extend across 
