Protonemertini, in which there are two layers of dermal muscles, external circular and internal longitudinal; the nervous system lies external to the circular muscles; the mouth lies behind the level of the brain; the proboscis has no stylet; there is no caecum to the intestine.
_This stylet is thus situated terminally when the proboscis has reached its maximum eversion.
This aggressive character has a different aspect in several genera which are destitute of a central stylet, but in which the surface that is turned outwards upon eversion of the proboscis is largely pro- P. vided with nematocysts, sending the urticating rods of different sizes in all directions.
There is reason to suppose that, when a wound is inflicted by the central stylet, it is envenomed by the fluid secreted in the posterior proboscidian region being at the same time expelled.
4) where the stylet is attached serve for this purpose.
- Proboscis with stylet, " reserve " sacs and muscular bulb of a Hoplonemertine.
The body contains in miniature all the organs of the adult fluke, including the gonads and in addition "eye-spots," a stylet, rod-cells and cystogenous cells.
In this process it is aided by the stylet with which it actively bores its way, throws off its tail FIG.
The stylet A (process of the 8th abdominal segment-8) is turned over to show its groove a, which works along the tongue or rail b.
III., 1st maxilla; a, base; b, sheath; c, stylet; c', muscle.
Barrois, " Le Stylet crystallin des Lamellibranches," Revue biol.