86 Mr. W. D. Lang—Revision 
with regard to, the aperture. [In Haplo- 
cephalopora these ayicularia are not con- 
spicuous on the greatly prolonged aper- 
tural ring. | 
1, No secondary front wall is formed, or, if 
so, it is formed by the swamping of the 
intraterminal front wall by secondary 
tissue. 
a. Paired avicularia, if on the apertural 
ring, stand out laterally on each side 
of the aperture 
6. Paired avicularia tend to disappear i in 
the greatly prolonged apertural ring . 
2. A secondary front wall tends to be formed 
by the secondary tissue around the 
aperture spreading proximally and 
laterally ec 2Seaeiiaace ans xc eee iele 
B, Secondary aperture always present and 
built up in connection with three, four, 
or more avicularia around the aperture. 
1. CEcia of small size, about 3 mm. long; 
less secondary tissue 
2. CXcia large, about 1 mm. long; more 
secondary tissue 
of the 
Il. Tricephalopora. 
Il, Haplocephalopora. 
Ill. Phractopora. 
BNL ta i IV. Polycephalopora. 
V. Antropora. 
I. TRICEPHALOPORA, gen. nov. 
Genotype. T. triceps (Marsson). 
Tabular Diagnoses of the Species. 
A. Paired avicularia not carried up on to the 
apertural ring so as finally to fuse over the 
apertural bar; in some cases they are directed 
proximally. 
I. Apertural ring incomplete laterally. 
a. Smaller, an mm. long; more “secondary 
[NER doo aeons saa cade me AS) aoe 
6. Larger, 3-3 mm. long; less secondary 
tissue. 
1. Avicularia somewhat irregular, some 
proximally directed and some proxi- 
mally placed with regard to the 
APEITUTE 20. ccc eee ttc eee ee 
2, Avicularia regular and laterally ig 
with regard to the aperture 
II. Apertural ring complete. 
a, Avicularia blunt and round. 
1. Avicularia regular and all distally 
directed. 
#. Median area of costal fusion smaller . 
B. Median area of costal fusion larger. 
a. CEcia hardly longer than broad 
b. CEcia nearly twice as long as 
broad. .)./:/.i% 2 ek eee 
2. Avicularia rather irregular and some 
proximally directed 
eeeene 
1. T. prenuneia. - 
2. T. ansata. 
3. T. vermicularis. 
4. T. capitata. 
5. T. brevis. 
6. T. galeata. 
7. T. somptingensis. 
