372 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



Family Exochellidae new family 



The frontal is a pleurocyst with radiating costae and a series of 

 areolar pores; the aperture slants downward and forward and has no 

 proximal sinus (rimule) and no cardelles; the well-chitinized operculum 

 bears a bordering sclerite for attachment of the opercular muscles ; avi- 

 cularia are usually well developed, frequently paired opposite the aper- 

 ture, and oral spines are well developed and sometimes jointed. 



Genus ESGHAROIDES Milne-Edwards, 1836 



Peristo?nella Levinsen, 1902. 



The aperture is oblique, without lyrula, cardelles or rimule. Ovicell 

 hyperstomial, embedded, opening above the primary aperture. The 

 frontal is a pleurocyst, with areolar pores. A small mucro usually pro- 

 jects into the secondary aperture from the proximal lip of the peristome. 

 Avicularia are usually paired at the sides of the peristome, directed more 

 or less laterally. Oral spines present. Genotype, Cellepora coccinea 

 Abildgaard, 1805. 



Escharoides praestans (Hincks), 1882 



Plate 43, fig. 12 



Mucronella praestans Hincks, 1882:168. 



A large attractive species, the zoarium unilaminar and encrusting 

 on shells, corallines, etc., white and glistening when young. Zooecia 

 robust, large, 0.90 (0.70 to 1.00) mm by 0.50 (0.45 to 0.60) mm, 

 much elevated distally. The front is a pleurocyst with large, deep areolar 

 pores in one or two rows, the pores often separated by strong ribs. The 

 peristome is much elevated on the proximal border, less so on the sides 

 and very little distally, moderately thin. A denticle ("umbo"), tri- 

 angular, quadrate or short spatulate, situated high up on or just within 

 the proximal tip of the peristome (similar in appearance to a lyrula but 

 not homologous). The secondary aperture is large, about 0.20 by 0.20 

 mm, directed forward, rounded-pyriform in outline ; on the distal border 

 there are 4 large conspicuous spines jointed at the base. The primary 

 aperture which, except in the very young, can be seen only after dissec- 

 tion is rounded proximally, without cardelles, the distal border is nearly 

 transverse often with a peculiar rounded lip projecting slightly inward 

 and backward. The avicularia are paired or single at the sides of the 

 aperture, varying in size and form from small and sharp-pointed to very 



