2 'in 



Synopsis of the genera. 



1) The inner surface of the frontal wall with a rounded cryplocyst 

 lamina (issuing from the proximal margin of the primary aperture), 

 the free margin of which is most often dislinctly visihle through the 

 frontal surface, esjjecially through its fenestrie: 



2) The hinge-teeth slightly developed and indistinct: 



3) The frontal surface with numerous, scattered pores; llu' inner 

 calcareous lamina short and broad and only seen distinctly from the 



inner surface of the frontal wall Cribricella n. g. 



3) The frontal surface with from three to twenty odd (more rarely 

 only a single) larger or smaller fenestra' or pores disposed in a con- 

 tinuous curve or in an angle; sometimes within the area bounded bj' 

 the fenestrje transverse fissures more or less regularly arranged in j)airs; 

 the free margin of the internal calcareous lamina generallj' clearly vis- 

 ible through the fenestrse. 



4) Within tlie area bounded by the fenestrse a larger or smaller 

 number of transverse fissures separating more or less developed, gener- 

 ally hollow spines. 



The lateral chambers wholly or almost wholly calcified; the ad- 

 zooecial, scapular chanii)er of the daughter-zooeciuni developed into an 

 avicularium Costicella n. g. 



4) No transverse fissures found within the fenestrse; at most 2 — 5 

 rudimentary spines on the proximal side of the aperture; lateral cham- 

 bers mostly membranous: the scapular chamber on the adzoa'cial side of 



the daughter-zocecium not developed into an avicularium Scuticellu n. g. 



2) Strongly developed hinge-teeth in the shajjc of robust, conical 

 or cylindrical processes, generally freely projecting within the aperture: 



5) The zooecia with 2 — 4 cylindrical, acropclal sj)ines distally, and 

 a rudimentary circular pedal chaml)er proximally; the aperture with a 



deep, rounded sinus Claviporella Mac Gillivray. 



5) No cylindrical acropetal spines: 



6) The aperture, not surrounded by a protruding margin; the four 

 lateral chambers forming on each side a continuous, wing-like mar- 

 ginal portion in the whole length of the zoaxium; the adzcxrcial side 



of the mother-zooecium with an avicularium Ptcrncellii n. g. 



6) The aperture surrounded by an acutely protruding sometimes 

 bilobate margin; the lateral chambers forming no wing-like marginal 



