246 MYRIOZOID^E. 



those of Microporella ciliata ; they are placed on small, 

 somewhat oval risings on the cell-wall. The mandible is 

 much elongated and attenuated above, and bears a de- 

 cidedly vibraculoid appearance; but it is expanded and 

 flattened towards the base, and the fixed beak is present, 

 though in a rudimentary condition. They are properly 

 ranked as avicularia, but exhibit a transitional form. 



SCHIZOPORELLA SIMPLEX, Johnston. 

 Plate XXXV. figs. 9, 10. 



LEPRALIA SIMPLEX, Johnst. B. Z. ed. 2, 305, pi. liv. fig. 4 : Gray, B.M. Bad. 

 118: Busk, B.M. Cat. ii. 82, pi. Ixxxiv. figs. 1, 2: Hincks, 

 Dev. and Cornw. Oat. 44 (sep.) ; Ann. N. H. ser. 3, ix. 204. 



Zooecia ovate, ventricose, very distinct, separated by deep 

 sutures; walls smooth, dense, greyish white; orifice 

 suberect, arched above, lower margin straight, with a 

 large central sinus ; peristome elevated and thickened, 

 forming a wall round the entire aperture; below the 

 mouth an umbo ; sometimes a small avicularium on one 

 side, about halfway down the cell, placed transversely, 

 mandible acute, directed outwards. Ooecia globose, 

 ample, smooth, usually with two or three umbonate 

 processes in front ; peristome in the fertile cells much 

 developed, forming a prominent, everted, semicircular 

 border. 



RANGE OF VARIATION. This is quite one of the least 

 variable of its tribe. The characters are strongly marked 

 and very constant. The avicularium, which has hitherto 

 been overlooked, is often absent, and seems never to be 

 developed on more than a few cells in each colony. 



HABITAT. On stones, shells, &c., from moderate depths. 



LOCALITIES. Off Sana Island, 40 fathoms ; coast of 

 Antrim, very abundant (Hyndman) : Belfast Bay, 20-35 



