SNAKES OF CEYLON. 187 



( 6) Entozoa : — The lung of the ratsnake is frequently found 

 tenanted by one or more worm-like parasites, or linguatulids, 

 to which Professor Stephens has given the name Porocephalus 

 pattoni. The adult parasite attaches itself to the lung tissue 

 by means of hooks; and there remains and sucks the blood of 

 its host. It is a grayish -white object surrounded by about 

 thirty -six rings or annuli, two of which encircle the head. It 

 grows to about 115 mm. (4f inches), and is about 2 '5 mm. 

 (J of an inch) in diameter. A head, neck, and body are 

 distinguishable. The head is globular, rounded dorsally, and 

 flattened ventrally. The mouth is shaped like an inverted 

 pear, and is surrounded by four strongly -curved hooks, by 

 which the attachment to the lung is effected. A fairly well- 

 defined neck separates the head from the body. The body 

 preserves an even calibre in its entirety, and ends in a blunt 

 extremity. Minute orifices — the cutaneous pores — are seen 

 on the head rings, and those in the anterior and posterior 

 parts of the body. A nearly allied parasite is shown in 

 figure 21. 



(c) Hxmatozoa: The red blood cells of the dhaman are 

 invaded by hosts of parasites called hsemogregarines. La veran 

 described this under the name Hgemogregarina zamenis, and 

 this is probably the same blood organism found by Patton in 

 Indian ratsnakes in 1908, and by Miss Robertson in Ceylon 

 specimens in the same year. (Fig. 39.) 



Fig. 39. — Hsemogregarina zamenis (after Miss Robertson). 



(a) Red blood cell. 



(b) The hsemogregarine. 



(c) Capsule of parasite. 



(d) Nucleus of cell. 



(e) Polar pigment of parasite. 



(f ) Nucleus of parasite. 



