The spermatozoon of arthropoda. XXII. The 12+0', 14+0' or aflagellate sperm of protura.

The spermatozoa of three genera of Protura are unconventional. Two of them, Acerentulus and Acerentomon , display hitherto undescribed axoneme patterns : ‘12+0’ in the former, ‘14+0’ in the latter. All the doublets are devoid of arms. The third genus, Eosentomon has a disk-shaped spermatozoon, devoid of tail. The presence of such unusual patterns is related to the non-motility of the spermatozoa.