68 UNIVALVES. 



Genus. CYPR^A.* JVwraJ, CyprcecB. 



Generic Character. f Shell univalve, involuted,]: 

 smooth ; form, suboval, resembling a coffee 

 berry, obtuse at both ends ; aperture linear, 

 longitudinal, extending the length of the shell, 

 effuse at each end ; lips curved inwards and 

 toothed ; the spire in some species just percep- 

 tible, in others its position marked by an um- 

 bilicus^ 



OBSERVATIONS ON THE SHELL AND ITS 

 INHABITANT. 



The Cypraeae, of which there are numerous 

 species, display a high natural polish, uniformity 



* Plate II. fig. 2, 4, 5. 



*f* The proposed manner of imparting instruction upon 

 Natural History, so as at the same time to develop the faculties 

 of children, having been fully shown in the preceding pages : 

 the substance only of the lessons will now be given for the 

 use of the Teacher ', who, it is supposed, will analyse it and 

 arrange it in questions according to the plan of the fore- 

 going lessons. A frequent repetition of the generic character 

 is recommended, and also that the children be required occa- 

 sionally to give a list of the parts of a shell, and definitions 

 of the terms they use. 



+ Involuted. Rolled inwards, this term is applied to a shell 

 when the first whorls are rolled within the body whorl, from 

 the Latin involut us 9 rolled up in. 



Umbilicus. A small hollow : this term was applied by 

 the ancients to the centre of the shield. 



