458 Our Fresh-Water Planarios. 



The above descriptions of these Planarian worins, partly 

 taken from my own observations and partly from Dr. Johnston's 

 catalogue, will, I hope, be found of use in helping some of my 

 readers to determine the species they may meet with. The works 

 I have consulted on this subject are Duges two valuable memoirs, 

 Diesing's " Systema Helminthum," 0. F. Mulleins " Vermium 

 Terrestrium et Fluviatiliurn," the " Prodromus ZoologigeDanicse" 

 of the same author; Oersted's " Entrouof Plattwurmer ;" Pro- 

 fessor Owen's artice on Entozoa in " Todd's Cyclopaedia of 

 Anatomy/' and Dr. Johnston's " Catalogue of the British Non- 

 Parasitical Worms in the Collection of the British Museum," 

 published by Taylor and Francis in 1865. The large work 

 of Miiller, " Zoologia Danica," contains several figures of the 

 Planarice, as also does Sir John Dalyell's work, " The Powers 

 of the Creator Displayed in the Creation," published by Yan 

 Voorst. The former work I have not seen, the figures in the 

 latter are not very good. There is also a treatise by Dalyell, 

 " Observations on the Planarian Worms." Dr. 0. Schmidt's 

 Treatise {" Die Ehabdoccelen Strudelwurmer ") is the best 

 work on the fresh-water Bhabdoccels. It contains numerous 

 figures of these animals. The researches of the same author 

 on the sexual organs of the Dendroccel Planaria, in the 

 " Zeitschrift fur Wissenschaftliche Zoologie," Band. x. and xi., 

 must be especially mentioned, but I regret I was unable to 

 consult the volumes at the time I was investigating the anatomy 

 of these worms, neither have I been able to meet with 

 Schuitze's " Bertriige zur Naturgeschchte der Turbellariea." 



Description of Plate. ' 



Fig. 1. — Planaria lactea, showing dendritic form of di- 

 gestive system (after Duges). 



Fig. 2. — The same species, drawn from a living specimen. 



Fig. 3. — Head of P. torva. 



Fig. 4. — Mesostoma rostrata, as it progresses. 



Fig. 5. — The same species when at rest. 



Fig. 6. — Full and side view of proboscis of ditto (from 

 specimen) . 



Fig. 7. — Head of Pohj cells brunnea. 



Fig. 8. — Capsulated ova of Mesostoma rostrata. 



Fig. 9. — Ditto of Planaria torva. 



Fig. 10. — Mesostomum personatum (from a specimen). 



Fig. 11. — Planaria torva, with protruded proboscis, swal- 

 lowing a worm (after Duges) . 



Fig. 12. — The same, in another position, attacking a 

 worm (after Duges). 



Fig. 13. — Pulycelis nigra, progressing. 



