stylet shaft decoration absent
Macrostomum infundibuliferum Fig 23.jpg

The penis-stilette is a slightly curved funnel with a widened base which is deeply indented. The external opening is terminal. p. 200
Macrostomum lineare Fig 5.jpg

The penis-stilette is a lengthy, tubular structure containing two right angle bends in its main axis. The basal proximal rim is dentate. The enlarged end is quite asymmetrical in that one side wall is always longer and larger than the other one. The sperm cell has a feeler, a conspicuous anterior swelling, lateral paired setae, but lacks a definite tail region. This cell lacks observable chromatin granules. p. 275
Macrostomum nassonovi Fig 6.jpg

This stilette is a completely bent spiralled and sharply pointed tube. p. 277
Macrostomum rhabdophorum Fig 26.jpg

Roughly crenated base. The termination is a very peculiar structure, three drawings of which are given better describe it (Fig. 22). Lateral, end, and dorsal views (a), (b), are shown. The sperm cell is a tapering filament which is possessed lateral setae in the posterior third of the cell. It is interesting note that the greatest number of sperm cells in this species is produced in the latter part of June, the warmest part of the summer in the Mountain Lake region. Also of interest is the fact that sperm is liberated in macerations of the animal will make attempts to penetrate the egg of the parent. The 'feeler' is a slowly undulating tactile organ as long as the sperm cell remains in the body of the animal, but it becomes a highly vibratile structure when in maceration. p. 289
Macrostomum obtusum Fig 7-10.jpg

An oval terminal external opening is provided. p. 278
Macrostomum orthostylum Fig 11-12.jpg

The singular sperm cells are particularly well described as lengthened fine threads which have an undulating feeler at one end. The major portion of the cell is spindle-shaped and contains a non-spherical nucleus enmeshed in an hyaline cytoplasm. Axial and spirally arranged filaments are present In the cell. p. 280
Macrostomum ruebushi var finnlandensis Fig 12-13.jpg

The penis-stilette is a funnel with almost a straight main axis and a sharply pointed and bent termination. The terminal portion enclosing the external opening is bent at an angle of 115 degree. The basal proximal rim is unevenly crenated. The sperm cells have a feeler, body region and a thin filamentous tail. Setae are not present. There is a noticeable massing of chromatic granules in the body region of the cell. p. 31
Macrostomum tuba Fig 13.jpg

The distal part of the stilette is slightly curved and has an expanded termination which is split in two parts. p. 128
Macrostomum viride Fig 25-26.jpg

Macrostomum timavi Fig 12.jpg
