242 



NATURAL UISTOliY. 



Malacobdella grossa, belonging to the family Malacobdellidse, is found between the mantle and 

 the branchiae of the Mollusc Cyprina islandica. It is nearly two inches long, and is flat, soft, 

 ringless, and of an uniform flesh colour. The Histriobdellidie have the posterior part of the body 

 split, as it were, and the head has tentacle-like processes. There are two horny jaws in the pharynx, 

 and the intestine is simple. Histriobdella komari lives upon the eggs of the Lobster, and it looks 

 like the larva of a dipterous insect. The next family, the Acanthobdellidse, have a flat fusiform 

 body, pointed in front and armed on either side by well-hooked sette. There is a posterior sucker, 

 at the bottom of which is the anus. 



The Branchiobdellidae have the body almost cylindrical in shape when it is stretched out. and the 

 segments are unequal. There are no eyes, and there are two flattened jaws, one over the other. 



There is a sucker at the posterior end. The species live on the 

 gills of Crabs and under the tail and at the base of the antennse 

 of the Lobster. 



Some Leeches, which have a more or less protrusible proboscis, 

 are termed the Rhynchobdellidse, and they are divided into the 

 Ichthyobdellidfe and the Clepsinidse. The first group are the Fish 

 Leeches, and the mouth is at the bottom of the anterior sucker. 

 There are four eyes. Some species of Piscicola live on fresh-water 

 fishes, others on marine fishes. The genus Branchelion has foliated- 

 looking lateral appendages, and lives on the Electric Ray and 

 on the Sole. In the Clepsinidse, which are short, flat, gradually 

 enlarged in front with three rings to each segment, and with an 

 oval sucker slightly distinct from the rest of the body, there are from 

 one to four pairs of eyes. The lower part of the body forms a 

 kind of pouch for the eggs, the embryos of which escape and hang 

 on to the mother. The proboscis is cylindrical, and the body is so 

 transparent that the viscera can readily be seen ; moreover, these 

 Leeches move in a geometric manner by their suckers, or can 

 UGA. B, XEHVOUS SYSTEM OF MALA- contract their body into a ball shape like a Wood Louse. They 



COBDELLA GKOSSA. (After Gcgenbaur ) ,1 i i j j.i i 11 .c i i i A' 



carry the young attached to the belly for a considerable tune 

 after birth. Clepsine bioculata lives in places with but little 



A, INTESTINAL TUBE OF 8ANGUIS- 



A. o, pharynx; c, ixisteri 

 eieoa ; a, anus. B. a, phan 

 6, Ilrst panglion of the lateral nervous trunk. 



l>alr of Intestinal 

 pbaryngeal ganglion; 



*-* tllc K b -^ i SPJ" | 8SLsj'ff; water, lurking under stones and beneath the bark of decaying trees, 



lion of other worms; 

 ganglia 



&' the succeeding 



and it feeds on the vegetable matter surrounding it, as well as on 

 fish. Some were fed by Sir J. G. Dalyell on a vermilion-coloured larva of a dipterous fly. " When 

 the prey was introduced to vessels containing the Leeches, they raised themselves on the sucker as 

 if surveying around ; then some one, bolder than the rest, advanced, and endeavoured to affix itself to 

 the victim, which, being effected, the position was pertinaciously maintained in spite of its writhings 

 and struggles." 



The Skate-sucker* belongs to the genus Pontobdella, which has a leathery knobbed skin, 

 and is about four inches long. It has no jaws, but it sticks fast and sucks out the juices of 

 the fish in a most cruel and pertinacious manner. Its eggs are contained in capsules, and 

 there is one young one to each capsule, which is attached to some substance or other in the sea, 

 Piscicola geometra, the Great-tailed Leech, is found on perch and carp and fresh-water fishes, and it has 

 large Buckets, in comparison with its size. The genus Hsementaria is used medicinally in Brazil ; it 

 has a two-lobed sucker. 



The genus Hirudo, comprising the true Leeches, belongs to the sixth family, and its description 

 has been given already. Associated with it in the same family are several genera, of which the 

 following are remarkable. The term Horse Leech is used rather widely, aud two genera have species 

 so named. 



Hceiitopsis sanguisuga is called Horse Leech by the French, and it lives in lakes and ponds, being 

 four inches long and half an inch broad. The long body widens backwards, and the large mouth has a 

 protruding upper part. It has ten eyes, and is green and black on the back and yellowish-green on 



* Pontobdella muricata. 



