598 yCJEMIFlC RECOKD FOR 1884. 



cial mouograph. These worms are not easily fouud ; to obtaiu tbem, it 

 is necessary to dig with a knife into moist ground, and especialty to seek 

 for them about the roots of trees. Tlie freshwater species are generally 

 found among the leaves of plants, hlauieuts of algse, or confervae, while 

 others are met with in the muddy bottoms of ponds and iSrooks. 



A rare hvman Tapeiconn. — At least eight species of tapeworms or 

 intestinal worms of the family TcvnUdcc have been found in the human 

 body in varying numbers. Of course, the most common are the Tivnia 

 solium and the Tcenia mediocanellata, the former being derived ordinarily 

 from pork, and the latter from beef. There is one species of the family 

 — the Tccnia {Hywevolepis) fatoimnctata — that has only once been ibund 

 in the intestines of man. It was in 1858 that Dr. Weinland discovered 

 some specimens discharged by a child in Boston. Dr. Leidy recently, 

 obtained evidences of the same species expelled from a child three 

 years old by a dose of santonin ; the specimens, consisting of a dozen 

 fragments, appeared to be portions of three worms, which reached a 

 length of from twelve to fifteen inches or more. Unfortunately the 

 head was lost, bnt enough remained to identify the species. ''The 

 mature eggs are spherical, measure some 0.072 millimeter in diameter, 

 and contain, fully developed, six hooked embryos." 



Although so rarely met with, it was thought by Dr. Leidy to be 

 probable that the worm is more common than would be supposed from 

 the rare instances of its observation, and that it has generally escaped 

 notice only " from its small size, and from the general ignorance of 

 the distinction, not only of this, but of the ordinary species of tape- 

 worms." Nothing is known respecting the life history of the worm or 

 its other hosts. {Proc. Acad. Nat. Sc. Pliila., 1884^ p. 137.) 



Kematelminths. 



The origin of the eggs and sperm of Ascaris. — The direction of the 

 studies of zoologists nowadays is well illustrated by several very elab- 

 orate memoirs on the genesis of the eggs and sperm in the common 

 intestinal thread-worm of the horse {Ascaris megalocepliaJa). One by 

 Dr. E. Van Beneden on the ovum and its fertilization takes up 375 

 Images ; another, by Van Beneden and Julin, on the spermatogenesis, is 

 30 pages long; and another, also on the spermatogenesis, by Dr. P. 

 Hallez, is 3 pages long. The most important of these memoirs is pub- 

 lished in the Archives de Biologic (iv, pp. 265-040, with 1 pL). 



Annelids. 



An American fresliicater Worm. — In certain rivers of Eastern Amer- 

 ica, beyond the inflow of salt or brackish water, is found a species of 

 tube-making chcetobranch worm which is closely related to certain sea- 

 worms, and which has no known relation in fresh waters elsewhere. 



