UNIVALVES. — BULLA, 81 



whereas, in the Cypraeae, both the pillar and outer lips are 

 strongly mounted with articulate and prominent teeth. 

 There is also a greater variety of form in the Bullae than 

 in the Cypraeae; as, for instance, the Bulla volva, or true 

 weaver's shuttle, is of an elongated form, having it^ 

 length much increased by two long beaks: this shell, 

 though far from beautiful, is accounted a great rarity, and 

 when fine bears a high price; it is from Jamaica and 

 the parts adjacent. There is also a variety of this shell 

 known by the name of the false weaver's shuttle. 



The next variation of form is discernible in the Bulla 

 ovum or poached egg^ of which there are two varieties: 

 the common sort (from Amboyna) is white without, and 

 yellow within ; the rarer sort (from the Friendly Isles) 

 is white without, and pink within. These shells arc less 

 beaked and more gibbous than the latter species, and 

 lead into the following orbicular or swollen species, such 

 as the Bulla naucum, physis, ampulla or lapwing's-egg, 

 &c. &c. These are without teeth, and somewhat umbi- 

 licated. 



There is a curious exception to the general form of the 

 Bullae in the Bulla terebellum or auger dipper, whose 

 shape is remarkably long and slender, and appears more 

 like a lengthened olive than what it really is. 



Some of the Bullae, as the ficus, and rapa or turnip, 

 are very similar to the genus murex ; the latter species, 

 i. e. the Bulla rapa, is esteemed a rarity. The former, 

 on the contrary, is common, and very much resembles 

 the shape of a fig. 



The Bulla zebra, bifasciata, achitina, and others simi- 

 lar to those, are land species; they are in form nearly al- 

 lied to the genus helix: and what is worthy of remark, 

 the animals which inhabit them are oviparous, their 



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