THE HOMARUS MARINUS. 457 
seven pairs of legs, which are furnished with an oar-like branch on 
the third joint. The abdomen has six segments only, and no 
appendages; and the tail or telson is flat and pointed, with a 
strong projecting central spine. In Fig. 3 M. Gerbe shows that 
the resemblance to the adult has become greater, but the great 
antenne, rostrum, and chelate extremities, and the appendages 
of the abdomen, are not yet developed. 
YOUNG LOBSTERS. 
1. Embryo in the egg. 2. Zoéa just born. 3. After the first moult. 
Let us examine Fritz Miiller’s description of the metamorphoses 
of a prawn, which is a stalk-eyed Crustacean, and closely allied to 
the lobster (from W. S. Dallas’s admirable translation of “ Facts for 
Darwin”). The young of the genus Peneus quit the egg totally 
unlike the adults, and the extent of the metamorphosis is as great 
as in any of the true Jzsecta. The youngest forms have, when 
they quit the egg, an ovate body without any segments; they have 
a solitary frontal eye, and three pairs of swimming feet, of which 
