theca operculata, Tremadoc beds.
"The Student's Elements of Geology"
Sir Charles Lyell
The theca is greatly distended over a variable extent of the cord; the cerebro-spinal fluid is increased in quantity and is under considerable tension; and the cord itself presents a shrunken appearance.
"Manual of Surgery Volume Second: Extremities--Head--Neck. Sixth Edition."
Alexander Miles Alexis Thomson
When the theca of the cord is directly infected the spinal symptoms predominate at first, but as the condition progresses it involves the cerebral membranes, and symptoms of acute general lepto-meningitis ensue.
"Manual of Surgery Volume Second: Extremities--Head--Neck. Sixth Edition."
Alexander Miles Alexis Thomson