202 Mr. A. Hancock on the Anatomy of the 



EXPLANATION OF PLATES II., III., IV. and V. 

 Plate II. 



Fig. 1. Upper portion of Fredericella sultana seen as a transparent object 

 very much magnified : a, tentacular disc ; b, tentacles ; c', mem- 

 brane at base of ditto ; c, flounced margin of ditto ; d, mouth ; 

 e, oral valve ; /, oesophagus ; g, projecting lips of cardiac orifice ; 

 h, stomach ; i, intestine ; j, anus ; k, nervous ganglion giving off 

 nerves ; I, tentacular sheath doubled upon itself ; m, strong ra- 

 diating muscles for preventing complete inversion of ditto ; n, de- 

 licate radiating muscles in connexion with the orifice of cell; 

 o, outer wall of cell ; p, inner wall or tunic ; q, inverted lips of 

 orifice ; r, the point where the same unite to the tentacular sheath, 

 immediately below which is the sphincter for closing the cell. 



Fig. 2. Retracted polype of Plumatella Allmani seen by transmitted light 

 and much magnified : a, bundle of tentacles enveloped in mem- 

 branous sheath ; a', tentacular disc ; b, oesophagus ; c, project- 

 ing lips of cardiac opening ; d, stomach ; e, intestine ; /, anus ; 

 g g, muscles for retracting the polype ; h, large radiating muscles 

 for preventing complete inversion of tentacular sheath ; i, delicate 

 radiating muscles in connexion with the orifice of cell \ j, outer 

 wall of cell ; k, inner membrane or tunic ; I, inverted margin or 

 lips of orifice ; m, tentacular sheath ; n, sphincter contraction of 

 ditto ; o, bud in second stage of development ; p, tentacular sheath 

 of ditto forming ; q, retractor muscles in an incipient state. 



Fig. 3. Upper portion of the cell of Plumatella Allmani much enlarged : 

 a, bud in first stage of development attached to the inner surface 

 of lining membrane of cell. 



Fig. 4. Cell with exserted polype of Fredericella sultana much enlarged 

 and seen as a transparent object : a, tentacular disc ; b, oral valve ; 



c, oesophagus ; d, stomach ; e, intestine ; f, the two bundles of 

 polype retractors ; g, two fibres of same for rotating tentacular 

 disc ; h, egg in connexion with ovary, attaching it to lower end of 

 stomach and wall of cell; V, appendage to the lower end of stomach, 

 probably generative ; i i, outer wall of cell ; jj, lining membrane 

 or tunic ; k, bud in third stage of development ; I, tentacles of 

 ditto as they at first appear ; m, stomach of do. ; n, retractor muscles 

 of ditto ; o, nucleated cell — the incipient egg in connexion with 

 the ovary. 



Fig. 5. Bud in third stage of development more highly magnified : «, ten- 

 tacular disc ; b, oesophagus ; c, stomach ; d, intestine ; e, incipient 

 egg in enlarged portion of ovary ; /, wall of cell. 



Fig. 6. Egg and ovary much enlarged of Fredericella sultana : a, egg im- 

 bedded in ovary ; b, wall of cell to which lower end, c, of ovary 

 is attached ; c', upper portion of ovary leading to stomach. 



Plate III. 



Fig. 1 . Side view of exserted tentacular apparatus much enlarged of Plu- 

 matella punctata : a, oesophagus ; b, oral valve ; c, tentacular or 

 oral arms ; d, tentacles ; e, membrane at base of ditto ; /, laminaj 

 at back of ditto. 



Fig. 2. Enlarged view of under side of tentacular apparatus of Plumatella 

 Allmani : a, margin of orifice of cell ; b, intestine ; c, oesophagus ; 



d, oral valve ; e e, oral arms ; f, membrane at base of tentacles. 

 Fig. 3. Enlarged view of the upper side of tentacular apparatus of Pluma- 



