294 li. M. Bri/(h>)ie — Fiti flier Notis on the TrinituiiKjIiuin Chalk. 



preserved. Lar<;e vicarious specialised cells, possibly vibracularia, 

 occur scantily but regularly. They are long, rather narrow, ancl 

 constricted towards the lower en<l. The aperture is situate at the 

 lower end, and is round below and pointed above. The lower two- 

 thirds of it are enclosed by the cell-wall, and the upper one-third by 

 a depressed front wall, which occupies the rest of tlie area. 



Mkjibuanipoua Trimminghamknsis, sp. nov. (Fig. 2.) 

 Colony adherent, growing as a rule in one direction only. Cell 

 elongated and pear-sliaped, with an oval aperture occupying with its 

 marginal wall (wiiich has its edges bevelled off) ratlier more than 

 liaJf the cell, the lower part forming an external area and tapering 

 awaj'. On the marginal wall is a single row of denticles. At the 

 upper end the marginal wall is exceedingly thin, which is easily 



Fig. 2. 

 seen, owing to the free edge of the ovicell being concave. Ovicelt 

 globose, narrower than in the preceding species, but similarly placed 

 at, the head of the aperture. Aviculariuin placed above the ovicell, 

 oval with an oval aperture, divided into two lobes (the upper being 

 slightly the larger) by two lateral denticles, which were joined by 

 a slender bar, which is generally destroyed. This species can 

 almost be constructed from the preceding one by rounding and 

 smoothing all sharp angles and corners. 



Mejibkanu'oka Bkitannica, sp. nov. (Fig. 3.) 

 Colony adherent. Cell subcircular to oval, the marginal wait 

 chiefly a common wall. On the foot of practically every cell 

 is placed either the ovicell or the avicularium of the cell below. 

 The ovicell is of the semi-globose type, but wide, flattened, and 

 steep-sided, so as to appear almost rectangular. Its free edge 



Fig. 3. 



a. Group of cells showinj: ovicelU and perfectly preserved aviculariuiu. 



b. Cell \\\i\\ usual type of avicularium. 



coincides exactly with the outline of the cell-wall beneath. 

 Avicularium mandibular and placed transversely with the point of 

 the mandible indiflerently to the right or left. It is generally 

 stumpy {h), but in well-preserved specimens the point is long and 



