288 MYEIAPODA. 



thus fitted to direct the movements of more perfect limbs. The legs, 

 therefore, as a necessary consequence, are now proportionately powerful, 

 divided into distinct joints, and provided with muscles calculated to 

 bestow on them that activity essential to the pursuit and capture of 

 active prey. Thus, then, by a simple concentration of the nervous 

 masses composing the abdominal chain of ganglia, we have the slow- 

 moving and worm-like Julus (which we have seen to be, in consequence 

 of its feebleness, restricted to live upon roots and dead substances) con- 

 verted into the carnivorous and powerful Scolopendra, well able to wage 

 successful war with the strongest of the insect tribes, and not unfre- 

 quently formidable, from its size, even to man himself. 



(742.) The mouth of the Scolopendra is a terrible instrument of 

 destruction, being provided not only with horny jaws resembling those 

 of insects, hereafter to be described, but armed with a tremendous pair 

 of massive and curved fangs ending in sharp points, and perforated 

 near their termination by a minute aperture, through which a poisonous 

 fluid is most probably instilled into the wound inflicted by them. It is 

 to this structure that the serious consequences which in hot climates not 

 unfrequently result from the bite of one of these animals must no doubt 

 be attributed. 



(743.) In their internal anatomy the Scolopendridce resemble insects 

 even more nearly than the Julus. The alimentary canal is straight and 

 intestiniform, but of much smaller diameter than that of the vegetable- 

 eating Myriapoda. It presents an oesophagus and a small muscular 

 gizzard ; but there is no perceptible division into stomach and intestine. 

 The respiratory and circulating systems, so far as they are understood, 

 seem to correspond with what we shall afterwards find to exist in the 

 larvae of insects. 



(744.) In the Scolopendridce, as we learn from the researches of 

 Mr. Newport*, the heart is enclosed in a distinct membranous covering, 

 which may be regarded as a true pericardium, consisting of a loose deli- 

 cate membrane, between which and the sides of each chamber of the 

 heart there is a slight interspace. The heart itself is a long pulsating 

 organ, corresponding in its general structure and position with the 

 dorsal vessel of insects ; it is situated immediately beneath the integu- 

 ments, and runs along the mesial line of the dorsal region of the body, 

 consisting of a series of chambers, twenty-one in number, that com- 

 municate with each other and extend through the entire length of the 

 animal from the tail to the cephalic segment. 



(745.) The minute structure of the heart is exceedingly interesting. 

 This organ is composed of two distinct contractile tunics, one external 

 and the other internal, each being covered by its proper serous mem- 

 brane. The external tunic is a very thick muscular layer, the fibres of 

 which are loosely interwoven with each other. The internal tunic is 

 * Phil. Trans. 1843. 



