CHAPTER I. 



DESCRIPTION OP A FLORA WITHIN ANIMALS. 



The most extensive associated flora and fauna wliich I liave discovered witliin ani- 

 mals exists with wonderful uniformity within the intestinal canal of tlie Mjriapod, 

 Julus maryinatus, Say, and of the Coleopterous insect, Passcdus cornutus, Fabricius; 

 and in order that the position of the parasites in relation to the diffei'ent portions 

 of the intestines may be clearly understood, I have considered it proper to give a 

 short anatomical description of the latter. 



§ 1. — Of tue Anatomy of the Intestinal Canal of Julus marginatus. 



(Plate Vn. Fig. 2L) 



The alimentary canal of Julns margiuafus, though extending in a straight line 

 from mouth to anus, is very large and capacious in relation to the size of the ani- 

 mal, and is in accordance with the nature of the food. 



Opening into the pharynx there are six salivary/ (/lands (Plate VII.), two of which 

 are pyriform («), conglomerate, and cellular in structure, and placed one upon each 

 side of the oesophagus; the others are long and tubular (b). 



The cesopharjus is pyriform and capacious {c). The proventriculus (d) forms 

 nearly half the length of the alimentary canal. It is capacious, cylindroid, and 

 dilates very gradually from its lower third to its termination. Its lower extremity 

 is constricted into si.x annuli, of which the last is twice the width of the others. 

 The mucous membrane of the proventriculus is smooth, ochreous-yellow in color, 

 and opaque. At the termination of the proventriculus, there open two hiliary 

 tuhes (e), and from it, surrounding the commencement of the ventriculus, is sus- 

 pended a broad, white, opaque, reticulated band (/), apparently composed like 

 the rete adiposa of insects. 



The ventriculus (g) forming about one-sixth the whole length of the alimentary 

 canal, is simple, cylindrical, or intestiniform, and is narrower than the proventri- 

 culus, and stronger. Upon its exterior surface, it presents several slightly tortu- 

 ous elevated longitudinal lines. Its lining membrane is smooth, and at the 

 commencement of the organ is provided with a single transverse row of thin, 

 quadrilateral corneous plates. 



The large intestine (Ji) commences very abruptly; at first being nearly twice the 

 breadth of the ventriculus ; but at its lower half, it gradually- decreases to its 



