SILVERY LAMPREY. 57 
Habiis—This Lamprey is usually seen in the spring, when it ascends 
small clear brooks, in large numbers for the purpose of depositing its 
spawn. ‘They are often found clinging to stones and clods of earth, in 
which position they are readily destroyed by the small boy. Later in the 
season they disappear, probably returning to deeper water, and are sel- 
dom caught except when attached to some unlucky fish, As they are 
rarely seen on their way down stream, ‘it is thought by fishermen that 
they never return, but waste away and die, clinging to recks and stumps 
of trees for an indefinite period ; a tragic feature in the scenery of the 
river bottoms worthy to be remembered with Shakespeare’s description 
of the sea floor.” (Thoreau.) 
They probably occur throughout Ohio, but are more abundant further 
northwest. They have, of course, no economic value. 
Genus 2. SCOLECOSOMA. Girard. 
Scolecosoma, GIRARD, U.S. Pac. KR. R. Surv., x, 384, 1859. 
Type, Ammecetes concolor, KIRTLAND, which is the larval form of Petromyzon argenteus, 
KIRTLAND. 
Etymology, skolex, worm; soma, body. 
Lampreys of rather small size, having the dorsal fin high and continuous, with only 
a shallow emargination ; the teeth nearly equal over the large buccal disk, the maxillary 
teeth two in number, pointed and set close together, without interspace and not form- 
ing a crescent shaped plate; mandibular plate with numerous close-set pointed cusps, 
which resemble distinct teeth. This genus differs from Petromyzon in the continuous 
dorsal], there being two distinct dorsal fins in the latter genus. Its known species in- 
habit the Great Lake region and the Mississippi Valley. The group was originally in- 
tended to include only those blind species (i. e. larve) which had a single dorsal fin, 
those larve with two dorsal fins being called by Girard Ammocetes. Tho type of 
Scolecosoma really seems to be a representative of a distinct genus, for which the name 
is of course to be retained in spite of the erroneous views entertained as to its relations 
by its author. 
2. SCOLECOSOMA ARGENTEUM (Kirtland) Jordan. 
Silvery Lamprey ; Wud Kel. 
Petromyzon argenteus, KIRTLAND (1840), Bost. Journ. Nat. Hist., iii, 342. 
Ichihyomyzon argenteus, JORDAN (1876), Man. Vert., first edition. 
Ammocotes argenteus, JORDAN (1878) Man. Vert., second edition, 
Ammocates concolor, KIRTLAND (1810), Bost. Journ. Nat. Hist., i, 473 (larva). 
Ichihyomyzon hirudo, GIRARD, (1859), U.S. Pac. BR. R. Sarv., x, 342.—GuUNTHER (1870), 
‘Cat. Fishes Brit. Mus., viii, 507. 
Ammocates hirudo, JORDON, Man. Vert., second edition, 350. 
Anmocetes epyptera, ABBOTT (1860), Proc. Acad. Nat. Sci. Phila., 327 (larva). 
