440 FAUNA HAWAIIENSIS 



II. Family Gigantorhynchidae. Large forms, whose body is ringed and 

 flattened during life like that of a Taenia. The hooks are like those of a Taenia, 

 the hook-papilla being entirely covered with chitin. There are two root-like processes 

 in 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 excentri- 

 cally 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 trans- 

 versely. The lemnisci are long, coiled, with a central lacuna. 



Genus Gigantorhynckus, with the characters of the family. 



Hamann includes three species in this family — G. echinodiscus, G. taenioides, and 

 G. spira ; and points out that E. 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 Myrmecopliaga jiibata and Cycloturus didactyla. 

 G. taenioides has been found in a species of Cariania, DicJiolophus cristatus ; and 

 G. spira lives in the king vulture, Sarcorhampus 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 MelolontJia vulgaris and Cetonia aurata in Europe and of Lachnosterna arcuata 

 in the United States \ It is recorded once from the human intestine. 



III. Family Neorhynchidae. 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, A^. clavaeceps and A^. agilis. They both 

 present interesting cases of paedogenesis, the large embryonic nuclei of the young 

 larva do not break up into numerous nuclei as they do in the commoner species. 

 A", agilis is found in Mugil auratus and M. cephalus ; A^. clavaeceps in the Carp, 

 Cyprinus carpio, its larva form according to Villot" in the fat bodies of the Neuro- 

 pterous insect Sialis niger ; it has also been found in the alimentary canal of the 

 leech NepJielis octocula, and specimens of the water-snail Linmaea have been artificially 

 infected with it. 



IV. Family Apororhynchidae. Short forms, with the body divided into three 

 well-marked regions, — head, collar, and trunk. The head is pitted, the collar smooth, 

 and the trunk wrinkled, not annulated — in spirit specimens. There is no eversible 

 introvert, and no introvert sheath, and no hooks. The sub-cuticle and the lemnisci 

 have a few giant nuclei, and the lemnisci are long and coiled. 



' C. W. Styles, Zool. Anz. xv. 1892, p. 52. 

 ' Zool. Anz. VIII. 1885, p. ig. 



