MASTIGOPHORA DUTEllTREI. 279 



Mastigophora DuTERTREij Audouiii. 

 Plate XXXVII. figs. 1, 2. 



Flustra Dl'tertrei, Audoinn, Expl. ; Savigny, Egypte, pi. ix. fig. 2. 

 Lepralia WooDiANA, Busk, Crag Pol. 42, pi. vii. figs. 1 & 3; Quart. Journ. 



Micr. Sc, Zooph. viii. 284 : Hincks, Quart. Journ. Micr. Sc. 



viii. 276. 

 Lepralia aurita, Reiiss, Bryoz. d. deutseh. Septarieutb. 62, pi. vii. fig. 13. 

 Lepralia otopiiora, Manzoni, Bryoz. di Castrocaro, 23, pi. iii. figs. 30 (not 



L. otophora, Reuss). 



Zoixcia ovate or rliomboid^ distinct^ usually punctured 

 round the margin ; surface granulated, the granules 

 frequently in radiating lines; orifice arched above, in- 

 ferior margin straight, with a slit in the middle, occa- 

 sionally an umbo below it ; peristome sometimes raised 

 and thickened in the fertile cells, and forming a wall 

 round the mouth ; marginal spines five or six ; on each 

 side of the orifice, near the top of the cell, a slender 

 vibraculum of moderate length. Ooecia globose, closely 

 adnate to the cell above, often subimmersed, sometimes 

 with one or two spines in front of them on each side. 



Colonies forming rather large crusts, with a tendency to 

 a lobate mode of growth. 



Range of Variation. There are two very marked forms 

 included under this species. In one (a), which is com- 

 mon in Shetland, the cells are of a greyish colour and 

 somewhat silvery, and the granules covering the surface 

 are disposed pretty regularly in lines which radiate from 

 the centre towards the margin. The row of large pores 

 round the base is wanting ; and the peristome in the fertile 

 colls is not raised and thickened in front ; occasionally 

 there is a slight prominence beneath the lower margin. 

 The vibracula are rather small. This variety is much 

 more delicate than the following. In the other (yS) the 

 surface is uniformly granular, and there is usually no 



