52 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
The mesenchymatous fibers before passing through the septulae traverse in 
the proximal part only of the zooecia small lateral chambers called dietellae ( = pore 
G x 100 H x 100 I X 100 
Fig. 8. — Structure of the pleurocyst. 
A. Ochetosella jacksonica Canu and Bassler, 1917, X 20. The calcification is active around 
the areolae. 
B. Mucronella granulosa, new species, X 20. Granular pleurocyst. 
C. Smittina grandifossae, new species, X 20. Pleurocyst with interareolar costules. 
D. E. Smittina angulata Reuss, 1865, X 20. Porous pleurocyst. In the interior the olocyst is 
perforated only by areolae (D). 
F. Mucronella variolosa Johnston, 1838, X 20. The pleurocyst is detached from the subjacent 
olocyst. 
G. Smittina reticuloides, new species, X 100. Tangential thin section in the vicinity of the 
olocyst. 
H. Smittina reticuloides, new species, X 100. Tangential thin section through the inter- 
areolar costules. 
I. Hippomenella rotula, new species, X 100. Tangential thin section through the pleurocyst. 
chambers of English authors) (fig. 9, O, D ) . These structures persist in fossilization 
only if their walls are thick; they may be discovered by abrasion of the frontal 
B x 20 
C x20 
D x20 
E x 20 
F x 20 
