284 



Drs. T. Cash and G. F. Yeo. [June 14, 



on crouching, and on its approximation of colour to that of 

 surrounding objects, whilst it rather waits for its food to come to it, 

 than attempts to pursue it. But the requirements of the trunk 

 muscles are much more similar in the two animals, and thus we find 

 the hyoglossus for procuring food, and the rec. abdominis for 

 spawning, respiration and flexion of the body, yielding very similar 

 values. 



Tortoise. 



In order to obtain a complete record of the long curve of 

 contraction of the tortoise muscle, and at the same time an exact 

 estimation of its latency, a second recording surface had to be 

 employed. The apparatus was therefore so arranged that the tendon 

 of the muscle drew upon the membrane of a Marey's tambour, which 

 acted as a weight beneath the lever which recorded on the plate of 

 the pendulum. By means of a second inverted tambour armed with a 

 light lever, the transmitted movement was written on a rotating 

 cylinder. The commencement of the curve including the time of 

 latency, was drawn on the rapidly moving plate of the pendulum, and 

 simultaneously a graphic record of the shape and duration of the 

 total curve was obtained on the drum. The results could be 

 associated after measurement of the tuning-fork curves, by means of 

 which the time was in each case controlled. 



Tortoise. 

 Table III. 



Muscles of Land Tortoise. Examined in "Winter. 



The muscles were prepared as rapidly as possible with their bony 

 insertions or attachments to the carapace preserved. Stimulation 

 direct maximal. 



Muscle.* 



Weight. 



Latency. 



Length of curve 

 to notch. 



Length of curve 

 to abscissa 

 (circa) . 





30 grms. 



•0225" 



•83" 



4"— 6" 



Semimembranosus 



30 „ 



•0247" 



1" 



4" 



Biceps fern 



10 „ 



•028" 



1-16" 



5" 



Ext. dig. com. . . 



10 „ 



•033" 



1-3" 



5 5" 



Of these muscles the first two are strictly parallel fibred. The 

 omohyoid is the agent chiefly concerned in the retraction of the head, 



* For nomenclature of muscles, see Bojanus, " Anatome Testudinis Europaeae," 

 Vilnas, 1849. 



