MAGILUS. 105 



We owe to the researches of Dr. Russell,, in Abyssinia, some 

 extremely interesting particulars relative to the habits of 

 this curious mollusk. He ascertained that the creature 

 inhabits masses of Madrepore, and that the worm-like 

 structure of his shell is occasioned by such a confined 

 habitat ; that, further, the formation of the shell originates 

 in the same spiral plan as that of similar moUusks, but 

 that, finding it needful to be in immediate communication 

 with the water, the Magilus is constrained to alter his spiral 

 mode of growth, in order to keep pace with the enlarging 

 surface of the coral. He pursues, therefore, a straight or 

 flexuous course, and renders the outer portion of his shell 

 extremely solid, in order to resist any pressure from without, 

 and that he may dwell safely within reach of the aperture, 

 by which he maintains a communication with the outer 

 world. The animal liimself rarely exceeds two inches in 

 length, although the shell is occasionally prolonged to at 

 least twelve or fifteen inches, by a gradual slipping of the 

 muscle of attachment along the columella, accompanied by 

 a copious secretion of calcareous fluid from the mantle. 



This species, like all coral-inhabiting mollusks, is nearly 

 devoid of colouring matter : the shell is of a transparent 

 alabaster white, and the edges of the mantle are tinged 



