H I 11 
8 . Hirudo viridis; body depreffed, and generally ob¬ 
long, but affumes feveral lhapes, though always pointed 
at the tail; body deep grafs-green, with a tranfparent 
border all round ; eyes two, black; eggs five or fix, oval, 
and deep brown. Inhabits clear cold waters; about an 
eighth of an inch long, and like moil of the g'enus has a 
power of reproduction almoft equal to that of the polype ; 
for, if the animal be divided in every direction, the parts 
will grow to perfeft animals, and may be again divided, 
and again reproduced, ad infinitum. This is molt con- 
1'picuous in the llagnalis, complanata, and oCtoculata, 
according to Dr. Shaw. See his Naturalift’s Mifcellany, 
and valuable p'apers on this fubjeCt in the Linnsean Tranf- 
aCtions. The viridis is delineated in feveral of its different 
fhapes, at fig. 4. 
9. Hirudo heteroclyta: body flattilh, pointed before, 
and broadilh behind; marked above with numerous fine 
longitudinal Itrise of black fpecks, and remote tranl’verfe 
brownilh ones, the farthest of which are black, with ful¬ 
vous fpecks ; head white ; eyes four or fix ; eggs nume¬ 
rous, l'phericai, green, furrounded with a pellucid ring ; 
the young ones that efcape firlt are yellow, the latter ones 
green. Trembley miltook this lpecies for a polype. Found 
in ftreams among aouatic plants; feven lines long; and 
often fixes itlelf on the inhabitant of the Helix planorbis, 
and lucks its juices: delineated at fig. 5. 
10. Hirudo geometra : elongated, yellowilli-green, with 
a row of white fpots ; body tapering before, and very broad 
at the tail-end ; eyes four; colour varying. Inhabits frelh 
waters, and fixes itlelf on the bodies of trout and other 
filh after the fpawning fealon ; eight lines long; moves hs 
if meafuring like a compafs. 
11. Hirudo teffellata: cinereous, with a teffellate margin ; 
eyes eight, in a double longitudind row; body dilated, 
and covered every where with bl. ck fpecks; above with 
orange or white fpots, or partly grey partly orange; be¬ 
neath grey, with two rounded white fpots in the middle. 
Inhabits rivulets ; about eighteen lines long. 
12. Hirudo marginata: body dilated, with a tellellate 
margin; eyes four; head obtufe before, and narrowed 
behind, white, pellucid, and marked with two tranfverfe 
brown bands ; abdomen reddilh-brown, with very minute 
itriae meeting beneath in double brown lines ; back with 
five rows of wliitilh dots, the lateral margin white, with 
a double brown line divided into fquare patches; tail or¬ 
bicular, pale, with brown Ipots on the margin. Inhabits 
rivers; ten lines long. 
13. Hirudo groffa: dilated, yellowifh, and divided on 
the fore-part. Found in the fea, ufually within the fhells 
of the Venus exoleta; about twelve lines long, and feven 
broad ; body marked with fine white flriie, the fore-part 
narrower and obtufe ; eggs very numerous, fpherical, and 
fwimming in a gelatinous fluid: delineated at fig. 6. At 
a, is Ihown a congeries of the eggs of this lpecies, as ex¬ 
cluded from the ovaria in a gelatinous mafs, examined 
under the microfcope, and figured by O. F. Muller, of 
Copenhagen. 
14. Hirudo hippogloffi: dilated, whitilh, with a double 
white eye in the middle of the body ; which is oval, de- 
prelfed, pellucid, a little pointed before, and ending in a 
globular ring behind ; head fomewhat triangular, with a 
cinereous fpot on each fide ; eyes not viilble; tail with a 
row of tubercles beneath from the centre, and towards 
the middle two hooks. Inhabits the fea; generally fixed 
to the Ikin of turbots and holibuts : delineated of its na¬ 
tural five at fig- 7. 
15. Hirudo crenata: body llightly depreffed, fuboval, 
greenifn, inclining to alh-colour, and tranfverfely ftriate 
with annular ftriae, from whence arife the crenatures of 
the margin ; eyes two, approximate; upper furface con¬ 
vex, lower flat. Found in lhallow Itreams, among aquatic 
plants. This is delineated of its natural fize at fig. 8 ; and 
a feftion of it, greatly magnified, at. fig. 9, to iiiow its in¬ 
ternal ftructure. 
x6. Hffudo muricata: body round, tapering, tubercu- 
u D O. 199 
late, and furnilhed with two fhort horns ; head larger than 
the tail; body ftrongly annulate, and tuberculate upon 
the rings ; tail very much dilated. Inhabits the fea; and 
adheres to filh, leaving a black mark on the fpot. 
17. Hirudo branchiata: depreffed, tapering, whitilh, 
with feven branched bridles on each fide; inteftines 
brown, bifid, pellucid; body foft, annulate, with fine 
wrinkles, and tapering towards the head; head fmall, 
truncate; tail large, round, dilated. Inhabits the Pacific 
Ocean, and adheres to turtle ; an inch long: delineated 
in the Engraving at fig. 10. 
It was for a long time the received opinion that the 
Hirudo medicinalis, and fanguifuga, were both viviparous, 
excluding their young like the eel, completely formed, 
and endued with aftive life; and it is but very lately that 
the contrary faff has been fuggeffed, and now fatisfafto- 
rily afcertained. Mr. Chriltopher Hebb, an eminent fur- 
geon in the city of Worcefter, having noticed in Buffon, 
and other writers on natural hiftory, that the hirudo me¬ 
dicinalis was laid to have brought forth its young alive, 
from thirty to eighty at a birth, he thought there was 
reafon to doubt the aflertion, and therefore made various 
long and careful obfervations, for the purpofe of invefti- 
gating the truth. “ Leeches (fays Mr. Hebb) will copu¬ 
late in a ftate of confinement, which I have feveral times 
leen, towards the dole of the month of April; yet never 
obferved this union to be productive. Leeches, too* are 
caught during the whole of the lummer-months, in which 
the production or multiplication of all the lower orders 
of nature’s works feems more particularly to be going on 
How then has it happened, that no leech has ever been 
caught in a ltate of gcjiation ; or, if it have, what has be¬ 
come of its offspring ? for no perfon has ever obferved the 
leech to bring forth its young, (if it be viviparous,) while 
under confinement. 
“ All thefe o'ojedions, (which I admit are purely of a 
negative kind,) vanilh before the prefurrtption that the 
leech is oviparous. That the ovum Ihould never evolve its 
contents, is readily accounted for, on the prefumption 
that glafs (in which leeches are ufually kept) is an im¬ 
proper nidus for that purpofe; as alio, perhaps, on the 
nbience of that juft; temperature and dired influence of 
the fun, which may be neceffary to produce fuch evolu¬ 
tion. To which maybe added, (in itfelf fufncient to ac¬ 
count for the failure,) that we are, every few days, chang¬ 
ing the water in which leeches are kept, thus difturbing 
the proceis that under more favourable circumftances 
might take place in the.otw, if fuch really exift; and in¬ 
deed, by this means, throwing them away altogether. 
Unlefs I have been much deceived, however, I have leen 
what convinces me that they are oviparous. In the month of 
May I have, from large leeches, leen protruding from the 
female organ of generation, a white opake oval fubftance, 
having a confiderable quantity of mucus adhering to it, 
which I cannot conceive to be excrementitious, but ra¬ 
ther an ovum .”—That this was the real fad, there can now 
be no doubt; fince all thefe ingenious obfervations of 
Mr. Hebb have been recently confirmed in France, by the 
celebrated naturalift M. Virey, author of a Paper on the 
Vermes, in one of the early volumes of the Journal de 
Phyfique, in which he affirms, that the Hirudo medicinalis, 
and fanguifuga, are both oviparous, producing numerous 
Ample eggs. The eggs of the fpecies called by Linnaeus 
oEloculata are, according to Bergman, a kind of capfules, 
each including feveral young. The eggs of the Hirudo 
medicinalis and fanguifuga are depolited on, or aggluti¬ 
nated to, water-plants, and are, in the words of M. Virey, 
femi-ovoides, leur coque ejl brune, cartilagincufe, & tranfparent ; 
“ femi-oval, the Ihell brown, cartilaginous, and tranfpa¬ 
rent.” 
Mr. Hebb, from further obfervations, conceives that 
the leech never grows in confinement; nor does he believe 
that it fuftains, in that ftate, any leniible diminution, ex¬ 
cept in thofe cafes in which it had, when taken, been 
gorged with the.blood of feme animal, or with fome other 
matter. 
