CHAPTER I. 



DESCRIPTION OF A FLORA WITHIN ANIMALS. 



THE most extensive associated flora and fauna which I have discovered within ani- 

 mals exists with wonderful uniformity within the intestinal canal of the Myriapod, 

 Julus marginatus, Say, and of the Coleopterous insect, Passalus cornutus, Fabricius; 

 and in order that the position of the parasites in relation to the different portions 

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

 short anatomical description of the latter. 



1. OF THE ANATOMY OF THE INTESTINAL CANAL OF JULUS MARGINATUS. 



(PLATE VII. Fig. 21.) 



The alimentary canal of Julus marginatus, 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 glands (Plate VII.), two of which 

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

 side of the oesophagus ; the others are long and tubular (6) . 



The oesophagus 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 six 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 Hliary 

 tubes (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 (h) commences very abruptly ; at first being nearly twice the 

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



