7 
II.—LERN AGA. 
The Lernx1p.%, although not so extensive a family in 
numbers of genera and species as the CaLiGipa, are more 
interesting to the specialist. They present some of the 
most remarkable instances of retrograde development that 
are to be found in the whole group of parasitic Copepoda. 
There is great excuse for the difficulty experienced by the 
earher Zoologists in giving certain members of this family 
their true place in the animal kingdom. ‘The fact that 
these animals were placed first in one group and then in 
another by successive workers is not surprising, consider- 
ing that nothing was then known about their life history. 
It requires some study even at the present day to show 
that Lernea is a Crustacean, still more to demonstrate 
that it is related to Lepeo phtheirus. 
The genus Lernea as it now stands contains only five 
species. Formerly it was very extensive, and included 
many forms, such as Lepeophthetrus pectoralis, that had 
not the least apparent resemblance to each other in the 
adult state. Careful research, along with a better know- 
ledge of the minute structure, gradually eliminated the 
unlike species, which were removed to other genera. An 
excellent historical account of our knowledge of the group 
will be found in Baird’s “ Entomostraca.” 
The species described here is Lernea branchialis, Linn. 
Mopr oF OccURRENCE. 
The adult female is found on the gills of the Gadide, 
such as cod, haddock and whiting. Immature (cyclops 
stage) males, and females with adult males attached, are 
found on the apex of the gill filaments of the flounder, 
sometimes in large numbers. Full-grown females are 
not plentiful on the fishes caught in the vicinity of Piel. 
