18 



ment that there was no dorsal sinus was based upon the examination 

 of a young specimen, a drawing of which I have in my possession which 

 certainly shewed no trace of dorsal sinus. I have seen it since in sec- 

 tions of an adult, the specimen examined may have been abnormal or 

 the dorsal sinus may be a late development and this specimen imma- 

 ture, there is however nothing in M. Jaquets description which does 

 other than support the theory of the two systems of spaces. 



Nephelis. There is here one point in the description Avhich I should 

 like to see reexamined viz. the direct communication (there is no- 

 thing in the text to shew that it is established by anything bigger than 

 a capillary) between each lateral vessel and the ventral sinus in the 

 posterior sucker. An examination of the figure (fig. 17), if we keep in 

 mind the direction which the circulating blood is likely to take, will 

 shew that the exact arrangement figured is not a very probable one. 



Pontohdella. Here I have no hesitation in saying that M. Jaquet 

 has entirely overlooked the dorsal, ventral and lateral vessels and has 

 described the sinus system alone. Vaillant as I stated appears to have 

 overlooked the lateral sinuses and the dorsal and ventral vessels. A 

 comparison of these accounts with my own will shew how exactly the 

 discrepancy between the Frenchman's accounts may be explained. 



M. Jaquet has added considerably to our knowledge of the system 

 of sinuses. He says nothing about what I have called the branchial 

 sinuses. I suppose the injection did not pass into them. It may be 

 that they are absent in P. verrucosa, I worked with P. muricata, this is 

 however exceedingly unlikely as they occur in a more or less imperfect 

 condition in all the genera of Rhynchobdellidae which I have exami- 

 ned, Pontohdella^ Piscicola, Clepsine and Branchellion. 



Clepsine. The author has as he admits not been so successful here 

 in his injections and consequently gives a very incomplete description. 

 He mentions Budge's paper in his bibliography, but although it con- 

 tains by far the best account of the vascular system he makes no fur- 

 ther reference to it. 



The vascular system in Clepsine still presents a most interesting 

 field for research. 



4. Vorschlag zur Gründung von zoologischen Stationen behufs Beobachtung 

 der Süfswasser-Fauna. 



Von Dr. Otto Zach arias, Hirschberg i/Schl. 



cingeg. 15. November 1887. 



Daß die Thierwclt des Meeres schon seit Jahrzehnten im Vorder- 

 grunde des wissenschaftlichen Interesses steht, begreift sich leicht, 



