722 DR WALTER E. COLLINGE. 



My lust thanks are here tendered to Professor W. C. M'Intosh for the facilities 

 he has so kindly given me for carrying out the work, and for material from the 

 University Natural History Museum and his private collection. 



I also wish to record my thanks to the Rev. T. R. R. Stebbing for specimens of 

 Zenobiana prismatica (Risso) and Stenosoma lanciferum (Leach) ; to Professor G. 0. 

 Sabs for examples of the Norwegian species of Idotea ; to Professor D'Arcy W. 

 Thompson for the facilities he has at all times so kindly given me for examining the 

 collections in the Museum of University College, Dundee ; to Dr Raffaele Issel for 

 specimens of Zenobiana prismatica (Risso) and other species ; to Dr K. Stephen- 

 sen for specimens of Idotea metallica, Bosc, and various species of Zenobiana and 

 Stenosoma ; to Professor L. A. L. King and Dr Thomas Scott for other species ; 

 and to Dr W. T. Calman for his kind advice on certain matters of terminology. 

 Finally, I have to thank Miss H. G. Kirk for the great pains she has taken with the 

 figures, many made from my rough drawings, and others direct from the specimens 

 themselves. 



Methods and Technique. 



Whilst examples of both sexes of all the species here enumerated have been 

 examined, many of them alive, dissections of all have been made and the different 

 parts treated in various ways to bring out the minute structure. A brief account of 

 the methods employed may prove useful. 



Killing. — Where living specimens have been obtainable these have been killed 

 by placing them in small glass jars and slowly adding equal parts of fresh water and 

 90 per cent, alcohol. When dead the specimens were transferred to 75 per cent, 

 alcohol, and finally to 85 per cent. Some species are apt to become very soft in the 

 75 per cent, alcohol, so that it is well to change them to the stronger alcohol after 

 an hour or two. 



Staining. — Various fluids have been tried, but only those possessing great 

 penetrative powers were found to be of any value. The best results were obtained 

 with Mayer's alcoholic carmine. When the parts were not required as permanent 

 mounts, very good results were obtained by leaving them for four or five hours in 

 an aqueous solution of methyl-green. 



Mounting. — All permanent preparations were treated with alcohol, xylol, and 

 mounted in Canada balsam (xylol). Temporary mounts were examined in xylol. 



For the removal of soft parts in the appendages, temporary preparations were 

 held, after mounting in Canada balsam, over a spirit lamp for about the third of a 

 minute. Where permanent preparations were desired, the different parts were boiled 

 in a weak caustic soda solution, then washed in alcohol, stained, cleared in xylol, 

 and mounted in Canada balsam. 





