General History of the Marine Polyzoa. 253 



Schizoporella circinata, MacGillivray. (Plate VII. fig. 1.) 



Loc. Napier, New Zealand (Miss Jelly) ; Victoria (Mac- 

 Gillivray) ; off Inaccessible Island, Tristan d' Acunha (' Chal- 

 lenger ' Exped.) . 



The figure of this species was prepared before I had recog- 

 nized the identity of the New-Zealand form with MacGilli- 

 vray's species. Indeed the specimens which I have examined 

 differ in some important particulars from his description and 

 figure. 



Instead of the single line of punctures round the margin 

 there is usually a belt of them on each side of the cell, the 

 central portion remaining smooth *. The peculiar avicu- 

 larium is not noticed by MacGillivray, nor is the broad ridge- 

 like mucro, rising into a point in the centre, which crosses 

 the cell a little below the orifice. The ovicell is peculiar in 

 shape, elongate, prominent, much elevated behind, narrowing 

 off rapidly towards the very small orifice, perfectly smooth, 

 faintly areolated round the margin (PI. VII. fig. 1, a). Busk 

 ('Challenger' Monograph, p. 166) describes a "curious 

 movable appendage jointed to the operculum," with which a 

 " minute fasciculus of muscular fibres " is connected. 



HlPPOTHOA, Lamouroux. 

 ? Hippothoa, n. sp. (PL VIII. fig. 4.) 



The form represented in the figure referred to above bears 

 a very close resemblance to the northern H. expansa, Daw- 

 son, if it be not identical with it. It also reminds us of some 

 of the numerous forms of the ubiquitous Schizoporella hyalina 

 which Prof. Smitt associated with Hippothoa. I must defer 

 further consideration of it for the present and merely call at- 

 tention now to the curious secondary cells (?) with which it is 

 furnished. These are minute, somewhat clavate in figure, 

 with a small roundish orifice at the extremity, and are 

 attached in considerable numbers to the normal cells. Fre- 

 quently one is placed on each side of the orifice. 



It is difficult to conjecture what their function may be, 

 but they may remind us of the rudimentary cells, often very 

 small, which are present on S. hyalina, though these are 

 much more highly developed. 



Loc. Napier, New Zealand. 



* My own figure is incorrect in representing the punctures as generally 

 distributed over the surface. The central portion of each cell is usually 

 occupied in great part by the ocecium of the cell below it, or by the large 

 avicularium, and (as a consequence probably) is always imperforate and 

 smooth. 



Ann. & May. N. Hist. Ser. 5. Vol. xv. 18 



