A Description of three Acoela from the Gulf of Naples. 309 
Genus 9. Amphiscolops. 
With many (—50) mouth-pieces, tali filament present. 
Genus 10. Polychoerus. 
The Classification of the Acoela by Luther (1912). 
I. Acoela without bursa seminalis. 
Family 1. Proporidae. 
A. Pharynx a long tube. 
Genus 1. Proporus. 
B. Pharynx wanting, or short. 
a) Penis paired. 
Genus 2. Childia. 
b) Penis single. 
aa. Body shield-shaped. 
Genus 3. Eaplodiscus. 
bb. Body cylindral. 
Genus 4. Rimi cola. 
IL Acoela with bursa seminalis. 
Family IL Convolutidae. 
A. With one genital opening, duct of f emale posterior to male. 
Genus 5. Otocelis. 
B. With one or two genital openings, female in front of male. 
a) Mouth-piece a soft tube or wanting. 
Genus 6. Äphanostoma. 
b) Mouth-piece lamellate. 
aa ) With one mouth-piece. 
1. Bursa opening into antrum femininum. 
Genus 7. Convoluta. 
2. Bursa opening into parenchyma. 
Genus 8. Monochoerus. 
bb) With two or more mouth-pieces. 
1. With one genital opening. 
a) Bursa single. 
Genus 9. Palmenia. 
b) Bursa composed of many sacs. 
Genus 10. Anaperus. 
2. With two genital openings. 
a) Mouth-piece 2—14 parts, no taii filament. 
Genus 11. Amphiscolops. 
b) Mouth-piece many (—50) parts, with filament. 
Genus 12. Polychoerus. 
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