374 ESCHARID^E. 



neither numerous nor important. The shape of the cell 

 varies to some extent, especially in crowded colonies ; but 

 it commonly exhibits the normal figure, which is slightly 

 contracted towards the aperture, and enlarged and rounded 

 off below. In the ordinary form the peristome rises in 

 front into a pointed central process, behind which the 

 median tooth is often completely concealed. This process, 

 which is a secondary growth, is more or less strongly 

 developed. In the very beautiful variety described by 

 Searles Wood from Crag specimens as Lepralia mamillata, 

 and which I have recently detected amongst Mr. Hynd- 

 man's dredgings on the Antrim coast, the peristome is 

 much produced in front and at the sides, and forms a thick- 

 ened and somewhat expanded border round these portions 

 of the mouth. 



The avicularia, which constitute so striking a feature of 

 the present species, vary considerably in size and, to some 

 extent, in position. Normally there are two of them ; but 

 one is frequently wanting; and when both are present 

 they are very often unequally developed. In the var. 

 mamillata, instead of being turned outwards towards the 

 side, they point straight upwards, and when the ovicell is 

 present they stand erect, one on each side, in front of it. 



The superficial changes to which M. coccinea is liable 

 are very remarkable. In its earliest condition the cell- 

 wall is of a greyish colour and very delicate texture, and 

 perfectly smooth. It is soon, however, invested by an 

 opaque crust, roughened on the surface, which after a 

 time takes on a distinctly granular character. In old and 

 deep-water specimens this granulous condition becomes 

 much more pronounced ; and in one very beautiful variety 

 the entire surface of both cell and ovicell is tessellated 

 with smooth white bosses or granules of various sizes and 

 shapes (Plate XXXIV. fig. 3). In var. mamillata there 



