32 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 50. 



nibalism. The development of the embryo in the egg is very slow. 

 Bancroft found that the egg did not begin segmentation before the 

 end of three months; Eailliet found that segmentation began in the 

 fourth month. Bancroft found the embryos formed in five months ; 

 Eailliet found the embryos formed in the fifth and sixth months. 

 The embryos in the eggs have been found alive as much as two years 

 and five months after embryo formation, the eggs being kept in 

 water. Galli-Valerio (1903) has developed embryos in two months 

 in 2 per cent formalin. 



The worms cause irregular white or yellowish spots on the liver 

 as a result of egg deposition, the spots suggesting coccidiosis. Sec- 

 tion shows a localized cirrhosis of the liver, the liver cells being atro- 

 phied and supplanted by connective tissue elements. In severe arti- 

 ficial infestations Bancroft found that three weeks after feeding the 

 rats showed signs of dyspnea, diarrhea, and emaciation, and died in 

 the course of three to four weeks. Animals less heavily infested 

 exhibit an atrophy of the liver which after the death of the worms 

 goes on to recovery, leaving only the localized cirrhosis. 



Hosts. — Epimi/s norvegicus {Mus decumanus), Efimys alexandri-. 

 nus {Mus alexandrinus) , (?) Lepus euroj)aeus. 



Location. — Liver. 



Local'lt'ies. — France, Italy, Australia, (?) England, United States 

 ( ?Philadelphia, Pennsylvania ; Washington, District of Columbia ; 

 Providence, Rhode Island; San Francisco, California). 



This parasite was first observed by Chaussat (1850). Other 

 records are those of Colin (1862), Davaine (1877), Leidy (1891), 

 McCoy (1908), Mink (1909), and Robinson (1913). Generali (1878) 

 notes the finding of encysted filiform nematodes in the liver of a 

 rabbit, causing nodules resembling those of coccidiosis and associated 

 with coccidiosis. Nicoll (1911) has recorded the finding of frag- 

 ments of a trichosome together with trichosome eggs in the liver of 

 Lepus europaeus in England, and I have tentatively referred his 

 record to Hepatlcola hepatica on the grounds that if the worm were 

 a species proper to and common in a food animal like the rabbit it 

 would be found of tener, as the lesions are almost sure to be observed. 

 To be sure, they might easily be regarded as coccidiosis, but the 

 numerous studies on coccidiosis of rabbits in turn should have insured 

 finding it. However, there are certain discrepancies between Nicoll's 

 description and that of //. hepatica. His measurements of eggs in 

 utero are slightly in excess of the maximum, 52 /*, found by me, 

 while the eggs found by him in the vagina attain a size of 70 to 78 /* 

 by 40 to 45 /n. He also finds the Qgg (fig. 36) to consist of a radially 

 striate outer shell, a concentrically striate inner shell, both incom- 

 plete at the poles, and an inner complete discrete membrane sur- 

 rounding the embryonic mass. I do not find a condition approxi- 



