Stridiilatioii iu Crustacea Decapoda. 65 



and one gets the impression of the different moods agitating 

 the animals during the pains of the work: eagerness, impatience, 

 fretfuhiess, weariness, exultation; and sometimes the whole 

 company makes a kind of chorus-cry for the measured regula- 

 tion of the work". 



And let us now turn to the stridulating organs in such forms 

 as the terrestrial crabs Ocypoda ceratophthalma and 0. macrocera 

 described above. It is instantly seen that they are more 

 highly developed than, for instance, those inNecropho- 

 rus, because they in the first-named species can produce two 

 \-er\- different tones, in the latter form even three tones. Whether 

 the animals really use this faculty is unknown (see p. 62), but 

 it may be supposed that they occasionally do so. And the topic 

 is, in my opinion, very interesting. But well planned — and, 

 for the rest, probably somewhat difficult — observations of 

 stridulating Decapoda and above all of species of Ocypoda with 

 highly developed organs are needed ; I even hope that this little 

 treatise may create interest in some Zoologist, who has an oppor- 

 tunity for biological obser\'ations in the field or perhaps in a 

 good "terrarium". 



