184 
CLASS V. 
[Note—The different species of Tetrarhynchus are, according to 
VY. SIEBOLD, nothing else than imperfect and sexless forms of tape- 
worms, which in the perfect and developed condition belong to the 
genus Rhyncobothrius of Rupotrm. These last are found only in 
the intestinal canal of Rays and Sharks. The embryos of Rhynco- 
bothrii make use of the bodies of other marine animals on which 
Rays and Sharks feed, as a temporary residence, until they attain 
to the intestinal canal of the latter by being swallowed together 
with their host. Such animals are Flat-fish, the Turbot, Barbel, 
Haddock, Gurnard, Conger-eel, Sepia ; in all of which young Tetra- 
rhynchi have been found. That in such situations they find only 
a temporary abode is proved by their being so frequently encysted, 
and by their restless state, for they perforate the flesh, the walls of 
the stomach, and the substance of the different organs, digging and 
boring with their four proboscides that can be forced in and out, 
and are covered with innumerable recurved hooklets. Von SreBoLD 
Band und Blasen-wiirmer, pp. 43, 44.] 
Family I]. Acanthocephala. Body utricular, roundish, marked 
with transverse rugee. Mouth none; proboscis retractile, covered 
with recurved hooks. Sexes distinct. 
Echinorhynchus Mur.u., Rup. 
Spiny-snouted worm. This genus (the only one of the family 
and of which the characters, therefore, coincide with those of the 
family) abounds in species which occur especially in the intestinal 
canal of vertebrate animals (mostly of birds and fishes). 
The largest species lives in the small intestine of the wild and tame hog, 
Echinorh. gigas CLoqurt Anat. des vers intestinaux, Pl. 5—8, BREMSER 
Icon. Helm. Tab. vi. figs. 1~—4. See for the anatomy CLoQuEt’s work ; 
comp. Burow Lchinorhynchi strumost Anatome. Diss. Zootom. Regiomonti, 
1836, 8vo. This Hechinorh. strwmosus lives in the small intestine of 
different species of Phoca. 
Family UI. Trematoda. Body depressed or roundish, soft. 
Suctorial pores. Mouth distinct; nutrient canal divided, mostly 
ramose. All the individuals hermaphrodite. 
or r 
Distoma Retz., Zev. (Fasciola L.in part). Body soft, depressed 
oundish. ‘I'wo suctorial acetabula; one terminal anterior, with 
perforated base leading to the mouth, the other ventral, situated not 
far from the former, impervious. 
