402 Mr. W. D. Lang—Revision of the 
or with slight fusion, or may be firmly fused medianly, and 
touching, but not fused laterally ; au apertural bar is either 
not formed or imperfectly formed (that is, the spines of which 
it is formed overlap and the subsequent fusion does not 
produce a bilaterally symmetrical structure) ; extraterminal 
front wall always visible and often considerably developed, 
especially proximally ; apertural spines, if present, four, 
never much enlarged; a secondary aperture never formed ; 
avicularia paired and generally pointed, primitively not 
large, narrow and straight, secondarily larger, wider, and 
curved towards the aperture, finally absent ; ovicells with a 
median keel or seam and, consequently, an aperture some- 
what mucronately pointed above, 
Tabular Diagnoses of the Genera and Species. 
A. Coste separate, not fused in the middle 
line, or very slightly so. 
1. Avicularia present; first pair of coste 
not larger than the rest ............ I, ANAPTOPORA. 
a. Avicularia large and pointed. 
1. Incrusting, unilaminar .......... 1. A. disjuncta. 
2, rect, cylindrienl er. ote arene she 2. A. cantabridgensis. 
b. Avicularia tend to dwindle and be- 
come blunt ; erect, cylindrical .... 3. A. mécklert. 
If. Avicularia absent; first pair of coste 
larger than the restand are notcurved. II. ANoropora inaurita. 
B. Coste firmly fused in the middle line, 
and laterally adjacent, but not fused .. III. Oropora auricula. 
I. ANAPTOPORA, gen. nov. 
Genotype. A. disjuncta. 
1. A. disjuncta, sp. n. 
Type-specimen. British Museum, D. 23269 ; Cenomanian ; 
Chalk Marl; Cambridge. 
2. A. cantabridgensis, sp. n. 
Type-specimen. British Museum, D. 21788 ; Cenomanian, 
Chalk Mar] ; Cambridge. 
3. A. méckleri, sp. n. 
Type-specimen. British Museum, D. 21858 ; Cenomanian, 
Chalk Marl; Cambridge. 
