220 TLATYHELMINTHES. 



P. solea 0. Sell. Plymouth, P. lenticulatum 0. Sclim. Isle of Man ; Byrsophlebs 

 Jen., B. Graffi, Jen. Plymouth, Millport, B. intermedia v. Gr. Isle of Man, Mill- 

 port; Proxenetes Jen., P. cochlear v. Gr., Millport. 



Fam. 5. Proboscidae. With a tactile proboscis, one or two generative 

 openings, separate germarium and vitellarium, bursa seminalis and compact 

 testes. Mouth ventral ; pharynx rosette-shaped. The continuity of the enteron 

 is interrupted at the period of sexual maturity. All marine except Gyrator 

 Ehbg. Pseudorhynchus v. Gr., Irish Channel; Acrorhynchus v. Gr., Brit, coast; 

 Macrorhynchus v. Gr., Brit, coast; Hyporhynchus v. Gr., Brit, coast; Gyrator 

 Ehrb., St. Andrews. 



Fam. 6. Vorticidae. With one generative opening ; germarium and vitellarium 

 combined or separate ; with accessory female apparatus, always simple uterus, 

 and compact paired testes. Mouth ventral, and usually near the anterior end ; 

 pharynx with a single exception cask-shaped. The chitinous penis very various. 

 Schultzia v. Gr. ; Provortex v. Gr., Brit, coast; Vortex Ehbg.; Jensenia v. Gr. ; 

 Opistomum 0. Schm. ; Derostomum Oers. ; Graffilla v. Jhering, parasitic ; Anoplo- 

 dium Schneider ; Fecampia crythrocepliala Giard, in gut of Carcinus maenas. 



Fam. 7. Solenopharyngidae. With one gen. opening, one germarium (ovary), 

 paired compact elongated testes. The pharynx elongated, tubular, directed 

 backwards. Solenophitrynx v. Gr. 



Order 3. ALLOIOCOELA. 



Enteron lobed or an irregularly widened sac. Testes follicular. 

 Paired ovaries and vitellaria, combined or separate ; vitellaria irregu- 

 larly lobed or partially branched. 



The parenchyma is less differentiated than in the Rliabdocoela, and 

 more in the condition it has in the Acoela. The generative openings 

 are separate or united, as in the latter group. With few exceptions 

 they are marine (Plagiostomum leinani. Lake of Geneva, Bothrioplana}. 



Fam. 1. Plagiostomidae. With one gen. opening, and without accessory female 

 apparatus (except Cylindrostomum} ; with testicular follicles in front of, alongside, 

 and behind the brain. Pharynx varying in position and size. Otocyst absent. 

 Usually small, cylindrical, or plano-convex forms with narrow hind end. 

 Acmostomum v. Gr. ; Plagiostomum 0. Schm. ; Vorticeros 0. Schm. ; Enteros- 

 tomum Clap.; AllostomumP. J. v. Ben.; Cylindrostomum Oers. All recorded 

 from British coast except Acmostomum. 



Fam. 2. Monotidae. With two gen. openings, and with bursa seminalis ; 

 testicular follicles closely aggregated between brain and pharynx. Pharynx 

 always elongated with opening directed backwards. With one otocyst. 

 Elongated forms with narrow front end and broad hind end. Monotus 

 Diesing ; Automolos v. Gr. Both recorded from British coast. 



Fam. 3. Bothrioplanidae.* Intestine with three branches, of which the 

 two posterior unite behind the pharynx. With one genital opening. Allied to 

 the Triclada. Genital glands with tunica propria. Bothrioplana Braun. , fresh 

 water. 



* F. Vejdovsky, Z. f. w. Z., 60, 1895, p. 198. 



