604 r>iv. 4. EADIATA.— I'IsTOZOA. Class 2. 



remains fiMctl there, and lives upon their blood. Tlicy contain two cords, sometimes of equal length 

 and at others long, and even doubled, which ai>peor to be ovaries. 



Lernaa, properly so called, have the body obloM;|- ; the neck loii? and slender, and the head siivrounded by a sort 

 of horns. L. branchialis, is the best known ; it infests the common Cod, and other fishes of the same family. 

 Its neck and head, the latter furnished with three hooks, are dark brown. It tixes itself tirnily in the si'-ls, and 

 adheres with the body bent in the form of the letter S. L. acuhiiis, which is more slender, and has two lon^- and 

 two short horns, attaches itself to the eyes of Herrings and other fishes. L. multicoi-nis has been found on thy 

 gills of a Serranus in the eastern seas. 



Pe/if^/n, have the head inflated ; the neck horny, with two short hooks on the nape ; the body lon^, furrowed 

 across, and ending in slender lilaments resembling the plume of a feather. P. filosa, which is seven or eight 

 inches long:, insinuates itself into the flesh of the Sword-tish, the Tunny, and other species, and causes them such 

 torment that they often dash themselves on the shore. 



Sphyrioii, have hooks at the mouth j the liead e.vteuded longitudinally like a hammer ; the neck blender ; and 

 the body flattened and heart-shaped. 



^Hf/(0)77/rt, attaches itself to the gills of fish by means of a single hook on the under part, which is directed 

 backwards. 



BrancMella, has two protuberances supporting the hook, by which it attaches itself. [One species, B. Salmonia, 

 infests Salmon, while they are in the sea, but drops otT after they come into the fresh water.] 



Chivella, attach themselves by the mouth only ; and Cuvier was of opinion that these two groups maybe united 

 with the LenieomifZie, or Sucking Lerna.>a, of De Blainville. 



C7iyH(/rrtf((;i^/(i«, besides the hooks at the mouth, have the edges of the body vnriorsly notched, or toothed: 

 some have a sort of two arms on eacli side ; some have many branched ones ; and others have a slender neck, and 

 deep notches in the sides of the body. 



Kcmertus, which may one day require to be made a separate order, are very soft-mouthed, slender, and long, 

 with the anterior extremity blunt, and the mouth large. The intestine extends the whole length of the body, and 

 is accompanied by the ovaries, which open near the mouth. One species, N. Barlai^ii, is more than four feet long; 

 it lui'ks in the sand, and sucks various MoUusca out of their shells. It occurs on the coast of Cornwall. 



Tubidaria and CerchrottiUi, of Renieri, and Uji/tiocep/uiltis of Quoy and Gaymard, ajipear to be analogous; but 

 little concerning them is known. 



THE SECOND ORDER OF THE EXTOZOA. 



PAREN'CIIYMAT.\, 



This order liicliulcs all tliesc Entozoa which have the body filled with a parenchyma, or 

 pidpy matter, cither in a cellidar tissue, or simply in the cavity, in which there is no alimentary 

 ap])aratus to be discovered, except a few canals, which carry nourishment to all the parts, and 

 which, in the majority of cases, originate in external suckers. The ovaries are also imbedded 

 in the parenchyma ; there is no abdomimd cavity, no intestine, and no vent ; and the signs of 

 a nervous system are fe\v and doubtful. The order admits of division into four families. 



THE FIRST FAMILY OF THE PARENCIlYiMATA. 



The Acanthocephala. 



These have a prominence, which a])pcars to act as a sort of prolioscis, and they attach themsehesto 



the coats of the intestines by means of the recurved spines with wliich the proboscis is beset. They form 



but one genus, 



Eciunorhynciius, — 



Which have ths body round, in some instances long, and in others shortened to a kind of sac. The 

 proboscis, by the hooks on wliich tliey attach themselves, is extensile, and contains a papilla, which 

 may be an organ of absorption ; but the animal ajjpcars to absorb moisture by its whole surface. The 

 oidy vestiges of internal viscera arc two small cocca attached to the base of the proboscis, and a longi- 

 tudinal thread which some regard as a nerve, and others not. Some species have an oviduct, but in 

 others the ova are diffused through the parenchyma. In the males, the organs are more distinct ; and 

 they n>ost likely impregnate the ova after they are excluded. They often perforate the coats of the in- 

 testines, and arc found in their substance, or adhering to their external surfaces. 



