442 F. W. GAMBLK. 



of the " Acoela " v. Graff gives some interesting additions to 

 our knowledge of the genital organs. The genital pore is 

 single. The testes are compact as in no other Acoelous form. 

 The vasa deferentia are merely their posterior prolonga- 

 tions. The oviducts are continuous with the epithelial lining 

 of the ovary, and unite to form a vagina. Opening into this 

 vagina is a spermotheca, the duct of which is slightly 

 chitinised. 



Habitat. — Among littoral algse, Plymouth Sound (F. W. G.). 



Distribution. — Naples^ Trieste, Dalmatian Islands (v. Graff, 

 55), Lesina (Schmidt, 28). 



Family APHANOSTOMID^. 



Acoela with two genital apertures, the female 

 pore placed in front of the male. A spermo- 

 theca present. 



Genus 3. — Aphanostoma, Oersted (21). 

 Spermotheca unarmed. 



3. Aphanostoma diversicolor. Oersted (21). 



Length "75 — 1 mm. Body somewhat fusiform, tapering 

 gradually forwards from the posterior third, more rapidly 

 backwards to the hinder end. The colour (which is variable 

 in amount and intensity) is due to violet pigment-cells and 

 yellow vacuoles in the parenchyma. These are usually dis- 

 posed in a characteristic way. The yellow pigment is present 

 at the anterior end, and extends a short distance backwards on 

 each side, enclosing the violet pigment which occupies the 

 median part of the body as far back as the limit of the 

 anterior third. A small patch also occurs at the extreme 

 hinder extremity. The violet pigment-cells are capable of 

 altering their shape according to the state of contraction of 



