HiLGENDOKF. — On Ncio Zealand Rotifera. 127 



one instead of four knobs, and that one posterior to the orifice 

 for the foot. Stomach enormous. 



Colour : Although almost colourless in itself, this Rotifer 

 is a very striking object on the stage, owing to the great mass 

 of dark-brown and dark-yellow food-matter it contains. There 

 is a rather small red eye cervically, and in some specimens 

 large pink-tinted eggs. In general shape this Rotifer is almost 

 round — indeed, its dorsal and posterior edges form a segment 

 of a perfect circle, and when the head and foot are retracted 

 the circle is almost complete. It is, however, evidently much 

 compressed, so that its roundness is that of a plate, not of a 

 ball, for no specimen that I observed ever moved off its side. 

 The foot is pendent from a small orifice in the lorica, about a 

 quarter of the way in front of the posterior end of the ventral 

 side. It is rather long, being able with its toes to touch the 

 corona ; but its chief characteristics are its worm-like flexibility 

 and its hyaline transparency. It is nearly always protruded 

 in a forward direction. The head is not marked off distinctly 

 from the rest of the body except by its protrusion beyond the 

 general outline of the rough circle, and by the line where its 

 invagination ends. It is not covered by the lorica ; it is very 

 flexible, and is almost constantly changing shape. It has 

 three indistinct lobes, or more probably a raised central 

 portion. It is in the slight depression at the junction of this 

 central portion with the general surface of the head that 

 invagination commences. The head is not retracted as a 

 whole, but the extremity is pulled in first, just as the tentacle 

 of a snail is, and the anterior part of the head can be seen 

 travelling backwards into the centre of the body, just as the 

 eye of a snail can be seen travelling down its tentacle. The 

 ciliary wreath is restricted in area, covering only the raised 

 central part of the corona, and having a circle of longer cilia 

 in the above-mentioned depression, at which the invagination 

 of the head commences. The lorica is not as much developed 

 as that of P. minuta. In no part has it the appearance 

 of such solidity, and in front, instead of having a well-defined 

 edge with two ornamental knobs, it merely dwindles away, 

 gradually merging into the unchitinized covering of the head. 

 One of the knobs, too — that guarding the orifice of the foot — 

 is missing, so that on the whole this may be taken as a less 

 specialised lorica than that of its generic companion. I ob- 

 served no dorsal cleft in the lorica, so that I have missed the 

 family characteristic ; but P. minuta is so distinctly a Salpi- 

 nidaean, and this is so distinctly a close ally of minuta, that I 

 have no hesitation in calling this too a Salpinidaean. The 

 mouth is situated at the ventral point of the circular depres- 

 sion. The gullet is very small yet distinct, and leads back to 

 the small, simple, and very slender mastax. After the mastax 



