or Little Known, Polyzoa. 105 



R. monilifera, M'G. 



(JR. monilifera, P. H. MacGillivray, Trans. Phil. Instit, 

 Vict, 1860 ; Hincks, Ann. and Mag., Nat. Hist, May, 1878.) 



Polyzoary foliaceous, variously convoluted. Fenestras 

 oval, narrower than the interspaces. Cells separated by 

 narrow raised lines, convex, smooth or granular. Primary 

 orifice arched above, straight below or hollowed, or with a 

 sinus. Secondary orifice with a sinus in the lower lip, 

 permanently .open or becoming closed in whole or in part, 

 at one side of which is generally a small oval avicularium. 

 Usually an elliptical avicularium on the front of the cell, 

 and others of various forms on different parts of the polyzoary. 

 Ovicells prominent, rounded or pyriform, with a beaded 

 or granular band above the orifice, from which extends 

 upwards a similar vertical band. Dorsal surface vibicate, 

 granular. 



This abundant species presents several forms so marked 

 that it may be doubtful whether they ought not to be 

 considered as species. In all, however, the mouth has 

 essentially the same structure, a fissure in the lower lip of 

 the peristome, with a small avicularium at one angle of the 

 opening. This fissure is sometimes closed by the complete 

 or partial coalescence of the opposite sides, leaving only a 

 loop-shaped mark or the lower end remaining perforated by 

 a round foramen. The angle supporting the oral avicularium 

 is frequentty much produced forwards. The other avicularia 

 are extremely various. There is generally an elliptical one 

 on the front of the cell, and forms with semicircular 

 mandibles are common. On the inner edge of many 

 of the fenestra?, one or more are found with long, 

 narrow mandible closing in a rostrum which has a sharp 

 tooth on each side towards the point. These open horizon- 

 tally inwards. In all, the ovicell is prominent and marked 

 by a beaded line immediately above the orifice, from the 

 middle of which a branch extends vertically upwards. In 

 sinuata the upper part of the vertical band frequently 

 projects considerably forwards, in munita it occasionally 

 ends in a sharp spine, while in umbonata it ends at the 

 base of a large sharp umbo. All intermediate forms may 

 be observed. The general form of the operculum is similar, 

 although somewhat modified in the different forms. In the 

 typical form it is thinner, more mitriform, and constantly 



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