7 i2 ENTOZOA. 



sucker against any object, and then extend the body well forwards. Having secured 

 the sucker of the head, they loosen their hold of the posterior sucker, arch their bodies 

 just like the looper-caterpillars, and so proceed. In the illustration of the common 

 leech, one of the specimens is shown in this attitude. 



Before bidding farewell to the Leeches, we must cast a casual glance at three re- 

 markable members of this group. 



The first is the BRANCHELLION or BRANCHIOBDELLA, a flattish and not very large 

 creature, which is notable for being parasitic upon the torpedo, and retaining its hold 

 in spite of the electric powers of the fish. Another species of the same genus is found 

 on the lobster. 



The second of these creatures is the wonderful NEMERTES, a leech-like being not 

 furnished with sucker, and attaining the extraordinary length of thirty or forty feet. 

 It is possessed of the most astonishing powers of extension and contraction, so that 

 a specimen of twenty feet in length will suddenly contract to three or four feet. No 

 one, indeed, seems to know the precise length to which a Nemertes can extend. 



It is always writhing and coiling its long body into apparently inextricable knots, but 

 never suffering any real entanglement, and has been known, without any apparent 

 reason, to convert its whole body into a long and slender screw. I should much like 

 to give a detailed account of this wondrous being, but am forced to pass to our next 

 illustration. 



The last of these beings is the LAND-LEECH of Ceylon (Hirudo Zeylonica,} a terrible 

 pest to those who travel through the forests, and often occurring in such vast numbers as 

 even to endanger life. On every twig and grass-blade the Land-leeches sit, stretching out 

 their long bodies towards the coming prey, and hastening after the traveller with dire- 

 ful speed. Instinctively they make for the unprotected parts. They crawl rapidly up 

 his clothes, they insinuate themselves into his neck, his coat-sleeves, and his boots ; 

 and wherever a patch of bare skin can be found, there a small colony of leeches is 

 sure to hang. 



Lank and thread-like as they are when they first assail their prey, they soon swell 

 to an enormous size with the blood which they imbibe ; and in the cases of horses and 

 cattle, hang in large clusters like bunches of black grapes. When travelling through the 

 forest, the last of the train are always the most pestered by the leeches ; for the blood- 

 thirsty annelids have been aroused by the passage of the pioneers, and hasten up just 

 in time to catch the rear-guard. Those who wish to gain a good idea of this leech 

 may do so by consulting Sir J. Emerson Tennent's " Natural History of Ceylon." 



WE now pass to the last members of this great class, the Entozoa, or Internal Worms, 

 so called because they are all found in the systems of living animals. They have also, 

 but wrongly, been termed Intestinal Worms, inasmuch as very many species inhabit the 

 respiratory, or even the sensorial, organs, and are never found in the intestines. The 

 Entozoa are very numerous, and are distributed throughout the world, inhabiting the 

 interior of various living beings ; and, indeed, their presence is so universal, that 

 wherever an animal can live, there are Entozoa to be found within its structure. 



To give an idea of the wide distribution of these strange beings, we will take one 

 genus of Entozoa as exemplified by the specimens in the British Museum, and note 

 the various animals in which the members of that single genus have been found. 



The restricted genus Ascaris is the type of its family, and many specimens are in 

 the collection of the British Museum. These have been taken from the following 

 animals : man, mole, dog, fox, cat, seal, wood-mouse, sow, horse, grizzly bear, heron, 

 tortoise (several), toad, frog, ruffe, blenny, fishing-frog, barbel, cod (several), turbot 

 flounder, eel, goshawk, barn-owl, lapwing, red-wing, cormorant, and grouse. These 

 are taken according to the number of the specimen in the catalogue, without any at- 

 tempt at arrangement according to their locality. 



