Abstract
The morphology of the sperm-head was studied in 9 species of the American rodents collected by Prof. S. Makino, with particular regards to the relationship to taxonomy.
The morphological features of the sperm-head show remarkable differences characteristic, not only to species but also to family. Particularly the variation in size of the sperm-head is very distinct between families. Generally there is a similarity in the feature of the sperm-head between the species belonging to the genus.
