NOTES. 363 



NOTE VIII., CHAPTER IL, p. 81. 

 ANAL RESPIEATION IN CRAYFISH. 



Lereboullet (" Note sur une respiration anale observee chez plusieurs 

 Crustaces ; " Memoires de la Societe d'Histoire Naturelle de Strasbourg, 

 IV. 1850) has drawn attention to what he terms " anal respiration '' in 

 young crayfish, in which he observed water to be alternately taken into 

 and expelled from the rectum fifteen to seventeen times in a minute. 

 I have never been able to observe anything of this kind in the uninjured 

 adult animal, but if the thoracic ganglia are destroyed, a regular 

 rhythmical dilatation and closing of the anal end of the rectum at once 

 sets in, and goes on as long as the hindermost ganglia of the abdomen 

 retain their integrity. I am much disposed to imagine that the rhyth- 

 mical movement is inhibited, when the uninjured crayfish is held in such 

 a position that the vent can be examined. 



NOTE IX. CHAPTER IL, p. 82. 

 THE GREEN GLAND. 



The existence of guanin in the green gland rests on the authority 

 of Will and Gorup-Besanez (Gelehrte Anzeigen, d. k. Baienzschen 

 Akademie, No. 233, 1848), who say that in this organ and in the organ of 

 Bo janus of the fresh water mussel, they found " a substance the reactions 

 of which with the greatest probability indicate guanin," but that they 

 had been unable to obtain sufficient material to give decisive results. 



Leydig (Lehrbuch der Histologie, p. 467) long ago stated that the 

 green gland consists of a much convoluted tube containing granular cells 

 disposed around a central cavity. Wassiliew (" Ueber die Niere des 

 Flusskrebses : " Zoologischer Anzeiger, I. 1878) supports the same view, 

 giving a full account of the minute strucMire of the organ, and com- 

 paring it with its homologues in the Copepoda and Phyllopoda. 



NOTE X., CHAPTER in., p. 105. 



THE ANATOMY OF THE NERVOUS SYSTEM OP THE 

 CRAYFISH. 



The details respecting the origin and the distribution of the nerves are 

 intentionally omitted. See the memoir by Lemoine of which the title is 

 given in the " Bibliography." 

 24 



