120 



is no connexion whatever between the cell and the cup placed im- 

 mediately above and behind it. The aperture of the cell is on the 

 anterior face, and towards the upper margin ; it is of a crescentic 

 form, and placed obliquely as it were across the upper or internal 

 angle of the cell, with the convexity of the curve directed upwards 

 and inwards. The lips of the aperture are strengthened by thin bands 

 of horny material, and under favourable circumstances, indications of 

 short, muscular fibres, for the purpose of opening or closing the aper- 

 ture, may be observed. This aperture, therefore, bears a strong re- 

 semblance to that of the cells in Gemellaria loricidata, figured by Dr. 

 Van Beneden, and of many other Bryozoa belonging to the same 

 sub-division. 



The cell which I believe to be entire at the bottom, though closed 

 only by a very delicate membrane, contains an ascidioid polype, any 

 detailed description of which I am unable to give, and which wpuld 

 perhaps be superfluous, as the animal did not appear to present any 

 peculiarity in which it differed from the typical form of that class of 

 polypes, now so well known to us from the labours of Milne Edwards, 

 Lister, Farre and Van Beneden. It has ten tentacula and no gizzard. 

 Two sets of muscular fibres, at least, may be distinguished as apper- 

 taining to the polype. The most important of these are the retractor 

 muscles, which, arising from the bottom of the cell, in the form 

 of long, somewhat flattened, transversely striped, isolated fibres, about 

 the -ny.Trijsth of an inch in width, are inserted some of them at the 

 base of the tentacles, and others lower down the body of the polype. 

 Other muscles, which may perhaps, as suggested by Dr. Farre, be 

 considered as the extensors, exist, in shorter transverse fibres, which, 

 arising from the sides of the cup, are probably inserted into the sac in 

 which the polype is contained. These fibres exhibit very distinctly 

 a nucleus, nearly in the middle of their length, and the portion of the 

 fibre between this nucleus and the wall of the cell is wider than the 

 other portion, and in that wider portion only, and there rarely, have I 

 been able to see transverse striae. 



With respect to the mode of development and the generation of 

 this Bryozoon, I have little to offer, want of time not having allowed 

 me to observe these points sufficiently in the living animal. But 

 with respect to the mode of development of the cells and tubes at the 

 extremities of the growing branches of the polypidom, it may be 

 stated that the posterior and anterior connecting tubes of the cells 

 and the two lateral cups, constitute, at the end of each branch, four 



