317 



Anarthropora (part) Smitt. 



The zooecta, which have no spines and are provided with scattered stellate 

 pores, have a well-developed vestibular arch. The primary aperture has a'straight 

 proximal margin and a membranous or very slightly chitinized operculum, which 

 is not separated from the compensation-sac. A short tube-shaped peristome, which 

 may have a small distal and a small proximal aviciilarium. No ooecia. Closely- 

 placed uniporous pore-chambers. In this genus there is only a single species, 

 A. monodon Busk. 



Inversiula Jullien^ 

 Microporella Hincks. 



The zocecia, which have no spines and are provided with scattered stellate 

 pores, have a distinct vestibular arch. A simple, strongly chitinized operculum 

 occurs, attached at its distal, straight margin. No peristome. A round ascopore. 

 Two small, lateral avicularia proximally to the aperture. No ooecia. Densely-placed 

 uniporous pore-chambers. 



To this genus belong /. inversa Waters and /. nutrix Jullien. 



The last two genera stand very close to each other and in addition to the 

 common characters mentioned in the diagnoses, some agreements in the structure 

 of the frontal wall may also be pointed out. We thus find a system of winding 

 canals, which open outwards through a circle of marginal pores, and in younger 

 zocecia the wall is distinctly composed of a mosaic of radiate, striated small 

 plates, each of which has a stellate pore in the centre. 



Escharoides^ Milne Edw. 



Peristomella Lev. ^; Mucronella Hincks p. p. 



Romancheina Jullien* p. p. 



The primary aperture, which may have up to 6 spines, is provided with a 



strongly developed vestibular arch, which has as a rule a thickened free margin. 



There is a strongly developed, often mucronate peristome, which may sometimes 



have an inner median tooth and is not separated from the primary aperture by 



any distinct boundary. The operculum is as a rule membranous, very rarely 



strongly chitinized and then forked at the tip. An avicularium may appear on 



each side, but is often wanting on one or the other side or even both on more 



or fewer zooecia. The ooicia, which are not found in all species however, have a 



' 45, p. 44. ' 84, p. 116. ' 56, p. 26. * 45, p. 60. 



