356 Rev. T. Hincks on British Zoophytes, 



conjectures that it may indicate a difference of sex, remarking that 

 it is more frequently absent than present. I have not found this 

 to be the case. The instances in which I was unable to detect 

 its presence were very rare. Amongst a great number of polypes 

 examined it occurred on all but a few. 



The connexion, however, now proved to exist between the 

 ciliated organ and the cercarice — which must be regarded as 

 spermatozoic bodies — may be accepted as conclusive evidence 

 that it is subservient in some way or other to the function of 

 generation. Professor Owen has pointed out "the analogy of 

 these cercarice with the spermatozoa discovered by Wagner in the 

 tortuous generative tubes of the Actinia ," and has noted their 

 importance in the generative ceconomy of the Bryozoa. I have 

 observed them in Bowerbankia as well as in Membranipora, and 

 Dr. Farre mentions them as occurring in Valkeria, Alcyonidium, 

 and others. They are no doubt present in all the members of 

 the tribe. 



May not the intertentacular organ be also the channel through 

 which the ova are expelled from the interior of the cell ? They 

 germinate, we know, from the inner surface of the lining of the 

 cell, and falling into the visceral cavity are there fertilized by 

 contact with the spermatozoa. It is probable that they find exit 

 through the same passage by which the cercarim were ejected, as 

 before described. 



In other species, Van Beneden asserts that he has discovered 

 the termination of the oviduct under the roots of the tentacula. 



I hope to be able ere long to report the results of further in- 

 vestigation into this interesting and obscure portion of the history 

 of the Bryozoa. 



Anguinaria spatulata. 



The mechanism of the cell in this pretty species is interesting. 

 The aperture, which is inferior, is large and oval. In the living 

 state a membranous covering stretches over it of a dirty whitish 

 colour. 



At the upper end is a small trap-door, which falls when the 

 polype is about to issue from its cell, and is drawn up and tightly 

 closed after it when it retreats. 



The polype does not protrude far from the cell. It has about 

 twelve arms. 



When retracted they may be seen folded together, and occu- 

 pying the anterior portion of the cell. The internal structure 

 is simple. There is a long oesophageal tube terminating in a 

 dilated bag or stomach. The polype, when withdrawn, stretches 

 down about two-thirds of the cell, and is not folded upon itself. 



Filaments descend from the base of the body to the animal 



