646 ENTOZOA. 



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

 and at others long, and even doubled, which appear to be ovaries. 



Lerruea, properly so called, have the body oblong ; the neck long and slender, and the head surrounded by a sort 

 of horns. L. branchialU, 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 fixes itself firmly in the gills, and 

 adheres with the body bent in the form of the letter S. L. acularU, which is more slender, and has two long and 

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

 gills of a Serranvis in the eastern seas. 



Penella, have the head inflated ; the neck homy, with two short hooks on the nape ; the body long, furrowed 

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

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

 torment that they often dash themselves on the shore. 



Sphyrion, have hooks at the mouth ; the head extended longitudinally Uke a hammer ; the neck slender ; and 

 the body flattened and heart-shaped. 



Anchorilla, attaches itself to the gills of fish by means of a single hook on the under part, which is directed 

 backwards. 



Branchiella, 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 off' after they come into the fresh water.] 



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

 with the Lerneomyzce, or Sucking Lernaea, of De Blainville. 



Chondracanthus, besides the hooks at the mouth, have the edges of the body variously notched, or toothed : 

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

 deep notches in the sides of the body. 



Nemertus, 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. Barlasii, is more than four feet long; 

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



Tubularia and Cerchrotula, of Renieri, and Ophiocephalus of Quoy and Gaymard, appear to be analogous ; but 

 little concerning them is known. 



THE SECOND ORDER OF THE ENTOZOA. 



PARENCHYMATA. 



This order includes all these Entozoa which have the body filled with a parenchyma, or 

 pulpy matter, either in a cellular tissue, or simply in the cavity, in which there is no alimentary 

 apparatus 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 abdominal cavity, no intestine, and no vent ; and the signs of 

 a nervous system are few and doubtful. The order admits of division into four families. 



THE FIRST FAMILY OF THE PARENCHYMATA. 

 The Acanthocephala. 



These have a prominence, which appears to act as a sort of proboscis, and they attach themselves to 

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

 hut one genus, 



ECHINORHYNCHUS, 



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

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

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

 only vestiges of internal viscera are two small cceca 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 most likely impregnate the ova after they are excluded. They often perforate the coats of the in- 

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



