MYRIAPODA, 



fat which surrounds it on all sides, are seen 

 to be perforated at intervals jc- -. 2 

 with numerous valvular ori- ' 



fices, through which the cir- 

 culating fluid gains free admis- 

 sion from the general cavity 

 of the body, and by the un- 

 dulatory contractions of the 

 dorsal heart thus constructed 

 is forced forward toward the 

 head. Arrived in the neigh- 

 bourhood of the oesophagus^ 

 the dorsal heart is seen to give 1 

 off several vessels, and ac- 

 cording to the opinion of Mr. 

 Newport and Mr. Lord,* there 

 is reason to suppose that a 

 vascular system more com- 

 plete than has as yet been 

 proved to exist in any of the 

 true Insects may be pointed 

 out in this region of the body. 

 The dorsal vessel itself, when 

 examined under a microscope, 

 is distinctly muscular, being 

 formed of circular flat bands 

 that surround the cavity of the 

 tube, so that doubtless the 

 action of this heart, in the 

 larger species at least, is suffi- 

 ciently energetic. 



Foramina npugnatoria. These are a series 

 of orifices which in the Julidse are seen upon 

 the lateral aspect of every segment of the body, 

 and communicate with as many minute mem- 

 branous sacculi placed within the body. These 

 sacculi, both from their position and relations., 

 forcibly remind us of the series of respiratory 

 sacs met with in the Leech and other air- 

 breathing Annelidans, but in Julus they are 

 supposed to be merely organs of secretion from 

 which some offensive fluid is poured for the 

 protection of the animal. 



Nervous si/stem. The nervous system of the 

 Myriapoda, as in all the Articulata, exhibits a 

 double series of ganglia connected by cords of 

 inter-communication. The supra-cesophageal 

 ganglion, situated within the cephalic segment 

 of the body as relates to its development, 

 seems to hold a place intermediate between 

 that of the Annelida and of Insects, or perhaps 

 more strictly speaking, corresponds with the 

 larva condition of the latter. The ventral chain 

 of ganglia is numerous in proportion to the 

 number of segments which enter into the com- 

 position of the body, their number decreasing 

 as the locomotive limbs over which they preside 

 become more fully developed and capable of 

 more vigorous action. Thus in Julus and 

 Geophilus, where the limbs are extremely 

 numerous and feeble, the ganglia in their num- 

 ber and small size approximate the condition 

 they exhibit in the Nereis or more elevated 

 Annelides, but in Scolopendra (fg. 313) the 

 more powerful limbs and stronger muscles 

 required by their carnivorous habits demand 

 greater developement of the centres of the ner- 

 vous system. 



Vide Med. Gazette for 1837. 



Fig. 31& 



I- 1 



Senses. In the structure of their organs of 

 sensation likewise, the Myriapoda so nearly 



