The internal anatomy and histology of the protonymph of the fish mite Lardoglyph1,ts konoi are descriped from paraffin, serial sections, viewed under immersion lens. The protonymph has a well developed body wall, muscular system, nervous system and a functional digestive system with a mouth and anal openings and specialised cells on the epithelium. The epithelial cells in the anterior part of the caeca contain characterostic spherules as in the adult. The nervous system consists of the supra-oesophageal ganglion, circum-oesophageal connectives and the ventral cord. The lateral fusion is complete on the supra-oesophageal ganglion, and demarcation into separate lobes, centres or tracts is not possible in the brain. The ventral cord has six separate clusters of cells, of which the anteriormost is the sub-oesophageal ganglion, and the others the segmental ganglia. Two cylindrical ridges about of 15 microns in length of undifferentiated protoplasm on either sides of the rectum form the genital rudiments.