ON ARHYNCHUS HEMIGNATHI. 215 
If. Family Gicanroruyncnipm. Large forms, whose body 
is ringed and flattened during life like that of a Tenia. 
The hooks are like those of a Tzenia, the hook-papilla being 
entirely covered with chitin. There are two root-like pro- 
cesses to each hook. The introvert is muscular, has no lumen 
and the introvert cannot be retracted into it, but the whole 
retracts into the body-cavity. The ganglion is excentrically 
placed to the side, behind the middle of the so-called sheath. 
The body-cavity is enclosed in a structureless membrane, and 
is traversed by membranes stretched transversely. The 
lemnisci are long, coiled, with a central lacuna. 
Genus Gigantorhynchus, with the characters of the 
family. 
Hamann includes three species in this family—G. echino- 
discus, G. tenioides, and G. spira; and points out that 
EK. gigas agrees with them in all points but that of the external 
annulation. The first of the above-named species occurs in the 
intestine of anteaters, and has been found in Myrmecophaga 
jubata and Cycloturus didactyla. G. tznioides 
has been found in a species of Cariama, Dicholophus 
cristatus; and G. spira lives in the king vulture, Sarco- 
rhampus papa. E. gigas in the adult stage occurs in the 
small intestine of swine, and its larval host is believed to be 
the grubs of Melolontha vulgaris and Cetonia aurata in 
Europe and of Lachnosterna arcuata in the United States.! 
It is recorded once from the human intestine. 
III. Family Neoruyncuipa#. Sexual maturity is reached 
in the larval state. The introvert sheath has a single wall. 
A few giant nuclei only are found in the subcuticle and in 
the lemnisci. ‘The circular muscles are very simply developed, 
and the longitudinal muscles only present in places. 
Genus Neorhynchus, with the characters of the family. 
This genus includes but two species, N. claveceps and 
N. agilis. They both present interesting cases of pzdo- 
genesis, the large embryonic nuclei of the young larva do 
not break up into numerous nuclei as they do in the com- 
1 C, W. Styles, ‘Zool. Anz.,’ Bd. xv, 1892, p. 52. 
