Thélohan, on Sporozoa, [94]

Thenea wyvillei, [212]

Theoconus, [79], [80]

Thermotaxy, [22]

Thigmotaxy, [20]

Thomson, Wyville, on Calcaromma, [83]

Thorax = second chamber of Monaxonic Radiolarian shell, [84]

Thyone, [573]

Tiara, [273]

Tiarechinidae, [557]