PEDICELLIN^ : PEDICELLINA. 885 



presenting in fact the appearance which the animal temporarily 

 assumes when disturbed. The body then becomes more opaque, and 

 at last falls off. After this the stalk retains its property of alter- 

 nately contracting and relaxing its different surfaces at intervals, 

 upon which its movements depend. After the lapse of a few days 

 the top of the stalk enlarges, and a minute head presents itself, in 

 which the different parts of the body are developed." 



The Pedicellina is the subject of one of Van Beneden's masterly 

 essays on the Bryozoa, to which the student of these animals may be 

 confidently referred for the fullest information, detailed in a clear 

 and lively manner, and illustrated with admirable figures. The ob- 

 servations of Professor J. Reid form a valuable supplement to the 

 memoir of the Belgian naturalist. 



The Pedicellina gracilis of Sars may be known by the stem 

 being quite smooth and free from prickles, and it is also thinner and 

 proportionably longer than in P. echinata. See Ann. and Mag. N. 

 Hist. XV. 382. 



The Pedicellina belgica of Van Beneden has also a smooth stem 

 and pedicle, but it bulges out about the middle, being narrower 

 both above and below. The polype has twelve tentacula, whereas 

 there are about twenty to P. gracilis. — Both these species may be 

 expected to be found on the British coast. 



The position of the remarkable genus Porbesia of PL J). S. Good- 

 sir (Ann. and Mag. N. Hist. xv. 380, pi. xx. fig. 4.) is uncertain. 

 Mr. Goodsir considers it equally related to Pedicellina and to Vorti- 

 cella, — " the link which connects the Infusoria just named with the 

 Polypi," — while Van Beneden maintains that it should rather be 

 referred to the family Echiuridse, in the class Echinodermata. 



c c 



