168 



^roup; the dorsal rib is composed of two, wliioh are widely separated only towards 

 their free ends. Spicula two; awl-shaped, bordered by a very narrow membrane; 

 the chitinous cylinder is apparently fenestrated. At either side of ibc genital orifice 

 are two knobbed papillaj. Female relatively stouter; vulva just in front of anus, 

 which is midway between it and the acutely pointed tail, usually covered by a hard 

 brown patch ; reproductive organs in two syrametrioal sets anteriorly directed, ex- 

 cept a small portion of one, which is at first posteriorly directed to form a loop in 

 front of the anus. Uteri two, in the caudal end of the body. These may be traced 

 up to the oviduct and ovaries, which continue to the cephalic end of abdomen, where 

 they are reflected to form a loop and thence continue bo the caudal end to form still 

 another loop. The ovary of the caudal uterus forms still another loop nearly oppo- 

 site the uteri. 



Eggs laid with gastrala inclosed; length, 0.09™™; width, 0.05™"". Embryos from 

 0.23'"™ upwards. The largest found in tumors were 4™™ long; the smallest male 

 fonnd in intestine was 7™™ long. The smallest embryos were without digestive ap- 

 paratus. The largest possessed an intestine, unicellular glands, and a well-formed 

 chitinous spherical cup in the head; also six cephalic papillai, and at the neck two 

 papilliE and a •well-defined fold. 



Occurrence. — The adults live in the large intestine of sheep below the 

 cfecum ; the embryos live in the intestinal walls in tumors, which, 

 though more abundant in the cfecum, may be scattered from the duode- 

 num to the anus. The species is distributed in the United States east 

 of the Mississippi River as far north as Maryland, perhaps farther uortli. 

 On comparing the species with others of the genus it was found that it 

 corresiioiided more nearly with CEsophagnstojna venulosum, a parasite of 

 goats, than any other described in modern works, and that it corre- 

 sponded still more closely with 0. acutam, Molln. {LI sottordine degli 

 acrofalli. Memorie dell * * * Istituto Veneto, 1860, Vol. IX, p. 

 449.) The latter is apparently a distinct species, although in quoting 

 other authorities he has given an incorrect synonymy. 0. Golumbia- 

 num differs markedly from 0. venulosum in not having an infljited necl;, 

 and from the latter and 0. acutum by the possession of a lapel of skin 

 upon the ventral side of the neck, just in front of the opening of the uni- 

 cellular neck glands. Molin examined two males and three females of 

 0. acutum from Antilope Bupicapra; one male from Capra Hircus, var. 

 Mambricus, in association with forty-five Sclerostoma hypostomum ; and 

 two males and one female from Capra Ammon. The finding of Scleras- 

 tomu hypostomum in association with tlie CEsophagostoma acutum is the 

 fact which leads me to infer that the latter occurred in the large intes- 

 tine of the above mammals and not in the stomach, as he cites in his 

 synonymy of the species. 



Life history. — CEsophagostoma Golumhianum seems to have become a 

 parasite of sheep since their introduction into this country. If present 

 in the Old World at all it is sparingly so, and seems to have escaped 

 detection. So little is known about its distribution, that it is impos- 

 sible at present to accurately define its limits. Prom its great abun- 

 dance in the Southeastern States one might infer that it had originated 

 as a sheep parasite in that region, and probably from some animal of 

 allied organization and ha,l>its. The writer is at present inclined to 



