316 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



SchizoporelHdae JulHen, 1903. The frontal is a tremocyst. 



Hippoporinidae new family. The frontal is an olocyst or pleurocyst. 



Exochellidae new family. The aperture is sharply slanted downward 

 and there are no cardelles ; frontal a pleurocyst. 



Microporellidae Hincks, 1880, There is an ascopore separated from 

 the aperture, frontal a tremocyst. , , ■u.r.^.',^J^ 



Family SchizOpOrellidae Jullien, 1903 (in part) 



This family as limited by Bassler, 1935, still contains numerous 

 genera. They are characterized especially by the tremocystal front which 

 is usually thickly and evenly perforated over the whole area, and by the 

 nature of the aperture and operculum. The proximal border of the 

 primary aperture usually bears a distinct and moderately deep sinus, 

 though in some genera (e.g. Hippodiplosia and Gemelliporidra), it is 

 broadly arcuate. The operculum, which is well chitinized, has the form 

 of the aperture; a narrow bordering sclerite and in some cases an addi- 

 tional sclerite inside from the border; the muscle attachments may be 

 removed from the border or on the margin. A vestibular arch is usually 

 present. The ovicell is hyperstomial and either open or closed by the 

 operculum. Avicularia are usually present, associated with the aperture 

 or scattered over the front. Spines are occasionally present. Cardelles 

 are small or wanting. 



Key TO THE Genera of Schizoporellidae 



1. Sinus a narrow linear notch 2 



Sinus broader and more rounded or arcuate 3 



2. Ovicell gigantic, completely covering the aperture . . Stylopoma'^^^ 

 Ovicell normal, not covering the aperture .... Arthropoma'^^^ 



3. Ovicell not closed by the operculum 4 



Ovicell closed by the operculum 5 



4. Avicularia in the midline proximal to the aperture . Schizomavella'^^^ 

 Avicularia not in the midline Schizoporella^'^ 



5. Aperture with a v-shaped sinus Schizolavella^'^^ 



The sinus, or poster, is wider, not v-shaped 6 



6. The poster is concave, moderately deep and much 



narrower than the anter Gemelliporidrd^^'^ 



The poster is wide, a broadly arcuate border 7 



