General History of the Marine Polyzoa. 125 



side of the lower margin, and somewhat overhanging the 

 mouth (the whole structure resembling a bird's head) ; man- 

 dible broad below, tapering off to a point above, apex in- 

 curved ; frequently on the front of the cell a pointed avicu- 

 larium, variously placed, the beak elongate, slanting upwards, 

 aperture contracted about the middle, mandible triangular, 

 basal portion of the avicularium extended into a pointed pro- 

 cess, which forms a rest for the mandible when thrown back. 

 Ooecia suberect, rounded, subimmersed ; surface smooth (or 

 sometimes nodulous), with a semicircular aperture in front, 

 filled in by a thin, flat, calcareous plate, hyaline and perfectly 

 smooth. 



Loc. Africa, on coral [Miss Jelltj) . 



This species affords a good illustration of the remarkable 

 changes in the appearance of the zooecium which may be 

 caused by the progress of the calcification. In its early con- 

 dition (as seen on the margin of the colony) the cell has a 

 slightly convex and perfectly smooth surface of very delicate 

 texture. The orifice is a simple opening, on a level with the 

 surface, and without any thickening or elevation of the mar- 

 gin. At this stage there is no trace of the oral avicularium. 

 In the second line of cells this organ is more or less perfectly 

 developed j the orifice is already immersed and concealed by 

 the risuig of the peristome and the thickening of the wall, and 

 the surface is dotted over with small vitreous nodules. In 

 the centre of the colony a great thickness of vitreous crust is 

 piled on the primitive surface of the cell, the orifice has dis- 

 appeared at the bottom of a deep shaft-like opening of irregular 

 form, and numerous nodular blocks overspread the surface, 

 which are frequently consolidated into a compact mass, in 

 which the avicularian rising is almost buried. The sutures 

 between the cells are now all but obliterated, and the zoarium 

 presents a continuous but uneven surface. The front 

 avicularia are developed on the superimposed crust. 



Schizoporella levaia, n. sp. (PI. V. fig. 4.) 



Zooecia small, disposed in lines, regularly ovate, convex, 

 strongly sutured ; surface perfectly smooth and shining ; 

 orifice arched above, lower margin straight, with a minute but 

 well-marked central sinus, peristome not raised ; below the 

 orifice an umbonate rising, which sends oft' an arm on each 

 side, so as to enclose it in front ; on its summit a minute cir- 

 cular avicularium. Omcium proportionally large, rounded, 

 expanded above, and narrowing towards the orifice, very 

 ventricose above, and somewhat depressed towards the open- 



