1870.) AND ECONOMY OF THE LAMPREYS. 847 
of Alosa finta, Mugil capito, and most other osseous fishes the ex- 
ternal lens-fibres are so deeply indented as to be well represented in 
that philosopher’s engraving from the Cod, these fibres in the Eel 
have merely a slight serrature or unevenness at their margins, the 
jaggedness not more distinct than in the same part of various higher 
vertebrates, as the English Batrachians, and the Rook and Rat ; nor 
in many cartilaginous fishes is the marginal denticulation of the lens- 
fibres much more marked, as may be witnessed in Acipenser sturio, 
Galeus vulgaris, Raia microcellata, and numerous others. 
And in the Lamprey even this feeble serrature of the edges of 
the lens-fibres disappears so completely that they are quite smooth 
and entire, except a very faint roughness towards the ends of the inner 
fibres near the poles of the lens. And the kernel of the lens is not 
so hard, tough, and difficult to be teazed out as in osseous fishes ; 
while in these last the lens-fibres are commonly much broader than 
those of the Lampreys ; as may be seen engraved (Monthly Journ. 
Microsc. Science, April 1869) from the River-lamprey, the Eel, and 
the Pike. 
OrGANS OF GENERATION. 
External Genital Papille, figs. 4 and 5, p. 848.—Some notices of 
these parts occur in the books of systematic ichthyology. Thus 
Yarrell says that ‘the roe, in both sexes, escapes by a small mem- 
branous sheath, which has internally at its base five apertures, one 
leading upwards to the intestine ;” and Couch describes, in the Silver 
Lamprey, “a process which perhaps appears only at the time of the 
shedding of the spawn, and may be confined to one sex only.” 
Wagner mentions ‘‘conical and often elongated structures, resembling 
intromittent organs, in Syngnathus, Gobius, Lepadogaster, Blennius, 
and also Petromyzon;” but as of the genital papillee and their tu- 
bular canal in both sexes of the Lampreys no notice is given either 
in the ‘Cyclopzdia of Anatomy,’ the ‘Comparative Anatomy of 
Vertebrates,’ or Max Schultze’s elaborate memoir on Petromyzon 
planeri, I have drawn up the following descriptions from this species. 
Penis or Genital Papilla of the Male, fig. 4.—This is very con 
spicuous during the height of the spawning-season in spring, and 
when flaccid is about an eighth of an inch long, a thirtieth thick, 
and of a conical shape. On the 20th of April, my son, while 
examining dead specimens of this fish under water, found that 
abundance of semen issued in a jet through the papilla, as from a 
syringe, when the abdomen was pressed between his thumb and 
finger ; and that this seminal outlet was a central and perfect canal, 
or longitudinal tube, through which either air or a fine probe could 
readily be passed from the peritoneal cavity. When the semen was 
pressed out in a full stream along this canal, the penis was elon- 
gated and somewhat distended and erected, like an intromittent part 
for copulation. The organ has numerous minute blood-vessels, and 
is composed of a dense connective tissue with numerous connective- 
tissue corpuscles. 
Female Genital Papilla, or Vulva, fig. 5.—At the same time we 
