QUESTIONS ON UNIVALVES. 143 



47. What is there particularly interesting in 

 the natural history of the Limpet ? 



48. What lesson has the poet drawn from their 

 natural history ? 



49. What is the generic character of the Den- 

 talium, and what its distinguishing mark ? 



50. What is the generic character of the Ser- 

 pula, and its distinguishing mark ? 



51. In what situations are Serpulae found, 

 and under what circumstances ? 



52. What is the generic character of the 

 Teredo ? 



53. What are the reasons for and against re- 

 taining the Teredo among the univalve shells 1 



54. Describe the work of the Teredo Na- 

 valis. 



55. What is the generic character of the Sa- 

 bella ? 



56. What is the generic character of the Nau- 

 tilus, and its distinguishing mark 1 



57. What kind of animal inhabits the Nau- 

 tilus ? 



58. What is there remarkable in the natural 

 history of the Nautilus 1 



59. What is the, generic character of the 

 Argonauta ? 



60. What position does the Argonauta appear 

 to occupy in the chain of nature 1 



61. Describe the habits of the animal inhabi- 

 ting the Argonauta. 



