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 



