

OVULTD^E. 243 



FAMILY OVULID^E. 



Shell related closely to the Cypraeidae in general form, but 

 differing in being involute in all stages of growth, whilst the 

 Cowries exhibit a short spire when young, which becomes 

 involute and more or less concealed by the enlargement of the 

 body-whorl with advancing age ; there is no epidermis, and the 

 porcellanous surface is usually smooth (sometimes lightly spirally 

 striate), sometimes gibbous, or transversely subcarinated, whitish 

 or not richly colored ; extremities more or less beaked, canalic- 

 ulated or emarginated ; aperture the entire length of the shell, 

 rather narrow, the inner lip smooth, the outer lip usually toothed 

 or plicate, sometimes smooth, indexed. Operculum none. Animal 

 covering the shell with its mantle-lobes after the manner of 

 Cyprsea, but the head furnished with a contractile snout rather 

 than a retractile proboscis. Dentition 3'1'3, the central tooth 

 being subtriangular, with several cusps, the laterals falciform, 

 with dentate margin, the marginals subnabelliform with finely 

 pectinated margins (PI. 1, fig. 10). 



Genus OYULA, Bruguiere, 1789. 



The characters are those of the family. H. and A. Adams, in 

 their " Genera of Recent Mollusca," have characterized a few 

 genera which it is convenient to retain, giving them the lower 

 rank of subgenera, however, as the main IVature distinguishing 

 them is the greater or less extension of the rostrated extremities, 

 a character of somewhat gradual development through the series. 

 The t3'pical group, which Messrs. Adams have distinguished as 

 Amphiperas, Gronov., has a Cypraeiform shell, ovoid, ventricose, 

 with but slightly rostrated extremities. The animal has a large 

 foot and the mantle-margin is simple. 0. ovum, Linn. 



There are fifty recent species, distributed throughout the world, 

 in warm latitudes only. A few cretaceous species have been 

 described; all of which, with a single exception (0. antiquata, 

 d'Orb., Cret. of India), are either Cypraeas or doubtful. The 

 genus is moderately represented in the tertiary. 



The genus Simnia, Risso, is characterized by its sharp outer 

 lip, and is still retained by authors, although, as first shown by 



