THE TRICHINELLIDAE 67 



the intercostal spaces; produce lymphangitis and peri- 

 lymphangitis which is sometimes acute, with fever; embryos 

 found in lymph spaces around the adult worms; life history 

 unknown; found in tropical Africa. 



A new species Onchocerca caecutiens has recently been 

 reported from Guatemala; this form is distinguished with 

 difficulty, morphologically, from O. volvulus; it produces 

 tumors and an erysipelas like condition of the head and neck. 



E. Family Trichinellidae 



Esophagus, a chain of single cells with intracellular lumen; 

 body divided into attenuated anterior region and thicker 

 posterior region, containing the reproductive organs; ovary 

 single, vulva at junction of anterior and posterior regions. 



I.- Trichuris trichiura (Plate VIII, Figs. 7 and 8) or the 

 whipworm. Anterior region of the body very long and 

 thread like; the posterior thicker portion truncated with a 

 terminal anus; male, with a spirally rolled posterior end; 

 length 40 mm. to 45 mm.; single spicule, which lies in a 

 retractile pouch beset with spines, 25 mm. long; female, 

 length 45 mm. to 50 mm.; thicker posterior region equals 

 two-fifths of body length; lives in caecum and sometimes in 

 the vermiform appendix, with its anterior end buried in 

 mucous membrane; infection direct; larvae within the egg 

 require a long period outside of body for development; 

 usually apparently harmless, but at times may give rise to 

 anemia and intestinal disturbances, and occasionally appen- 

 dicitis; distribution cosmopolitan. 



2. Trichinelia spiralis (Trichina spiralis). Male, length 

 1.4 mm. to 1.6 mm.; .width 0.4 mm.; anterior region of body 

 narrowed; orifice of cloaca terminal and lies between two 

 caudal appendages; internal to these are two pairs of papillae, 

 the dorsal one behind the other; female, length 3 mm. to 



