118 E.ev. T. Hincks's Contrihutions towards a 



give the prettily speckled appearance to the front wall of M. 

 inlosa. The margin of the aperture is not thickened as in the 

 latter ; and the two very tall spines near the bottom of the cell 

 are an additional feature. 



Membranipora variegata^ Hincks. 



[' Annals ' for August 1881.] 



The specimen on which mj description of this well-marked 

 and handsome species was founded proves to have been im- 

 perfect ; and an important character has been omitted. In 

 point of fact it belongs to the same group as our British M. 

 sjrhiiferaj which is characterized by the presence of small, 

 pointed avicularia, elevated on tall and slender pedicles. In 

 the present case there is some irregularity in the position of 

 these appendages; but when present tlieyare commonly situated 

 on one side of the cell, just behind the lowest of the two stout 

 upper spines. The pedicle is much attenuated towards the 

 base ; the avicularium is narrow and elongate, and the beak 

 scarcely bent at the extremity. 



I am indebted to Miss Jelly for the opportunity of examin- 

 ing a number of specimens of M. varicgcda^ and for drawing 

 my attention to the very interesting fact that it is also some- 

 times furnished with avicularia of the ordinary type. This 

 is the only case that has come under my notice in which 

 the two forms are present on the same specimen. In one speci- 

 men, at the top of almost every cell there is a rather small, 

 sessile or slightly raised avicularium, with the pointed man- 

 dible directed upwards. Occasionally three or four occur 

 about the upper part of the cell. 



In well-develo})ed colonies of this species there is a marked 

 contrast between the stout, tall, erect spines (usually six in 

 number) round the upper part of thezooecium, and the slender, 

 sharp, abruptly bent spines which protect the lower lialf of 

 it. They aie all furnished with a conspicuous black base. 



Membranipora coronata^ Hincks. 



[' Annals' for February 1881.] 



A specimen (probably from Ceylon) obtained by Capt. 

 Cawne Warren is furnished with the chitinous portion of the 

 avicularium, which was wanting in the one on which the 

 original diagnosis was founded. I am now able to add that 

 the appendage has a long vibraculoid mandible. 



