The Parasites of the Cockroach. 341 



(which is simply a slit in the tunic) by the action of long cilia 

 which are placed around it. A dense granular area extends 

 over a portion of the interior, and is the representative of the 

 female generative organ. A smaller cell is sometimes developed 

 on this larger mass, which contains the male generative par- 

 ticles. Spontaneous fission frequently takes place in these 

 Infusoria ; a portion of the nucleus and nucleolus, as the two 

 bodies just described are called, separating with the rest of the 

 animal. The Nyctotherus ovalis is oval in outline, and has the 

 tunic slightly inflected at the posterior part, the mouth is very 

 obvious, and the particles of food may be watched as they make 

 their descent into the general cavity of the body. In movement 

 it is very active, but seems to suffer considerably when placed 

 in pure water, where it soon becomes quiescent, and eventually 

 dies. It is evidently solely adapted for life in the thick and 

 dense fluids of the alimentary canal of insects. The maximum 

 transverse measurement of the Nyctotherus of the cockroach is 

 the j| 7 th of an inch. 



IScolecida. — Two species of parasites belonging to the class 

 Scolecida occur in the body of the Blatta. One is the Anguillula 

 or Oxyuris macrura, and is found in the interior of the intestine ; 

 the other is the Gordius orientalis, and occupies more rarely 

 the general cavity of the abdomen. The Anguillula (Figs. 13, 

 14) is a minute, transparent little worm, about the \ th of an 

 inch long, or less. The walls of the body are annulated, most 

 distinctly near the head, and are very elastic and transparent. 

 The alimentary canal extends throughout the greater portion of 

 the body, commencing in the first ring, where the mouth is 

 situated, and terminates after passing along nearly three-fourths 

 of the animaPs length. The body becomes very much contract! d 

 at this point, and is produced into a thin, tail-like appendage. 

 The peculiar-looking circular body marked b, is part of the 

 oesophagus, and, together with the succeeding dilatation marked 

 c, forms a very powerful and muscular apparatus. The intes- 

 tinal tube which follows these is nearly straight (d), and has 

 thickened walls, containing numerous brown granules, which 

 secrete a fluid intended to assist in the process of digestion. 

 The females, which, among the Nematodes, are larger and 

 more numerous than the males, are generally found full of eggs, 

 which are also seen floating about in the various early stages of 

 development among the other contents of the intestine. The 

 female generative organs (e) consist of a long ccecal tube, 

 which winds around the intestine, and contains ova in various 

 stages of development. An ovary, Fallopian tube, uterus, 

 and vagina are distinguished by comparative anatomists. 

 The ova in this species appear to float freely in the cavity 

 of the body when they have attained a certain stage of 



