THE STEPHANOCEROS. 65 



The transparent case, or mantle, which invests the 

 body of the Stephanoceros, is not an open rigid tube, as 

 in the Melicerta, but a flexible integument, which is 

 thrown into annular folds or corrugations when the 

 animal contracts itself; and, as the upper margin of this 

 mantle is attached like a collar round the body, near 

 the base of the rotators, its border becomes inflected 

 when the animal shrinks down towards the bottom of 

 the case, (see pi. ix, fig. 2), the tube being then like 

 the introverted finger of a glove. In this position the 

 tentacula are brought close together, side by side ; and 

 when the creature is about to protrude, the extremities 

 of the arms first appear united into a point, which 

 gradually lengthens, till the rotatory organs are wholly 

 excluded, and assume the form of an elongated dome, the 

 base of which surrounds the mouth. In some positions 

 the crown is depressed, and resembles in shape the cu- 

 pola of a mosque. From the different phases assumed 

 by the Stephanoceros, and its constant activity when 

 vigorous, for it will shrink into its crystal cell the in- 



in the marine polypes, (the Bryozoa, or moss animals, so named from 

 their investing other bodies like moss, of which the common Flustra is 

 an example), the Stephanoceros may be regarded as the link which unites 

 the Rotifera with the cilio-lrachiate (arms with cilia) polypes. The 

 manner in which the arms of this animalcule are protruded and withdrawn , 

 will remind the experienced observer of the similar action in the Flustrse, 

 &c. 



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