10 
ation shows that they deviate still less from the Copepod-shape 
than do the adults. "I shall describe these stages later, comparing 
them with the stages of metamorphosis which precede the state of 
insertion into the body of the fish. 
That our pårasite belongs to the family Lernæidæ is evident; 
in many points it agrees with genera like Pennella, Lernæa, Ler- 
næenicus and Peroderma. The 3 first-named possess 4 pairs of 
abdominal feet, the two anterior biramous, the two posterior uni- 
ramous; for this and other reasons the new parasite will hardly 
be accepted into any of these genera; more likely it might be 
included in the genus Peroderma, as the latter has only 3 pairs 
of swimming feet; but as we shall see presently, various structural 
differences seem to justify the establishing of a new genus and 
species for our parasite. I propose for it the name: Sarcotretes 
scopeli, and give the following diagnosis: 
Sarcotretes n. g. Body elongated; the middle portion of the 
genital segment constricted into a narrow, firmly chitinized stalk, 
only the distal, claviform part behind the stalk projecting outside 
the host; antennules linear; antennæ cheliform; one pair of maxilli- 
peds; three pairs of abdominal feet, the two anterior biramous, 
the posterior uniramous; three free abdominal segments with terga 
and ventral sterna well developed. 
S. scopeli n. sp. Cephalothorax with two large, thin-walled 
(ventro-) lateral outgrowths; no other outgrowths present. Dorsal 
shield fully preserved, oblong, with an upper chitinous curved line 
on each side; other chitinous stripes under the front margin, and 
along the base of the sipho; tergum of hindmost abdominal seg- 
ment small and narrow. 
Inserted into the body of Scopelus glacialis, the body wall of 
which it pierces, penetrating to the alimentary tract. 
The genus Peroderma was established by Heller (1865, 10, 
p. 250) for the species P. cylindricum (1. c. Pl. XXV, Fig. 6), which 
penetrates the lateral muscles of the Pilchard in the Mediterranean. 
H.'s description and figure were rather incorrect and were improved 
