NO. 2258. TAENIOID CESTODES OF DOGS AND CATS— HALL. 55 



distinctly overlap the anterior end of the uterus, whereas in related 

 tapeworms gravid segments show a tendency to become very dis- 

 tinctly separated and constricted at their point of contact with other 

 segments. The eggs are elliptical, 31 to 34 [x by 29 to 30 \i in 

 diameter. 



Hosts. — Primary : Canis familiaris. Secondary : Lepus europaeus 

 {L. timidus), L. calif ornicus, L. c. wallawalla, L. c. deserticola, L. 

 timidus {L. variabilis), L. calif ornicus texiamis {L. texianus), L. 

 callotis, Oryctolagus cuniculus, L. cuniculus doinesticus {L. cunicu- 

 lus), Sciurus vulpinus (?), ^S". niger neglectus (S. vulgaris), jS. caro- 

 linensis (?), Myocastor coy pus {Myopotamus coy pus). 



Location. — In the smaJl intestine of the primary host. In the con- 

 nective tissue of the secondary hosts, intermuscular, subcutaneous, etc. 



Localities. — England, Scotland, France, Switzerland, Italy, Russia, 

 Siberia, Australia, New Zealand, Japan, India, Tunis, and the United 

 States. 



Life history. — Eggs developed by the adult worm in the intestine 

 of the primary host pass out and are ingested by the secondary host 

 with contaminated food and water. In the digestive tract of the 

 secondary host the embryo escapes and bores into the tissues and 

 possibly into the circulation of the host. In the connective tissue 

 under the skin, between the muscles, and elsewhere, it comes to rest 

 and develops into a larval form, or coenurus, with numerous heads 

 attached and also with the production of internal and external 

 daughter bladders which in turn develop numerous heads. On in- 

 gestion of tliese bladders by the primary host the tapeworm heads 

 develop segments and form the strobilate worm. 



The thickness of this worm and the number of calcareous cor- 

 puscles make it an unfavorable subject for toto mounts. Unless 

 the calcareous corpuscles are eliminated by the use of some acid, the 

 resulting mounts will be very unsatisfactory, and even after they 

 are eliminated the thickness of the worm makes it a very much less 

 satisfactory mount than such translucent worms as M. muUiceps, 

 M. gaigeri, or even such worms as Taenia pisiformis. The descrip- 

 tion given above is based on specimens furnished to the United 

 States Bureau of Animal Industry through the courtesj- of Professor 

 Eailliet. Material from North America available to the present 

 writer through the courtesy of Prof. F. D. Barker, of the University 

 of Nebraska, appears to conform in essential respects to the European 

 form. 



In a previous paper (Hall, 1910) I have noted that the records of 

 this parasite from the squirrel were probably correct. Since then I 

 have recorded (Hall, 1911) the development of this species in Sciurus 

 carolvnensis. 



