A STUDY IN MOEPHOLOGY. 
105 
the hind body, as shown in the figure, and its hairs are short. As in Lucifer at the 
same stage, the exopodite is as long as the endopodite. 
The third pair of maxillipeds, and the first, second, third, and fourth pairs of 
thoracic limbs are represented by buds, as in Lucifer at the same stage. The bud for 
the third maxilliped (fig. 77, Mg). 3) is bilobed, longer than the others, and it points 
backwards outside the other buds. The buds for the first three pairs of periopods 
are bilobed, in contact on the median line, and about equal in size. Those for the 
fourth pair are much smaller, and are hidden in a ventral view by the buds for the 
third pair, but they can be seen in side view (as shown at T 4 in fig. 78). There is no 
trace of the fifth pair of pereipods either at this or at any later stage. Claus figures 
buds for the fifth pair in the Zoea of Sergestes, and also in the next or Acanthosoma 
stage of Sergestes; but the study of the Zoea of Acetes shows even more satisfactorily 
than is the case in Lucifer that these appendages are entirely absent, and it seems 
safe to believe that this is the case in Sergestes also until the larva of the latter has 
been carefully examined with reference to this particular point. 
The abdominal appendages, with the exception of the fifth pair, are entirely absent; 
but each abdominal somite has a pair of long ventral spines. The swimmerets are 
represented by long bilobed buds, which project beyond the fork or notch in the telson. 
The abdominal ganglia are very much more conspicuous than they are in Lucifer. 
The distribution of pigment is somewhat different from what we find in the Lucifer 
Zoea, and nearly all the pigment-spots are bright-red. There is a large spot of red and 
one of reddish-yellow on the eye stalk, a red spot on the labrum, a large red and very 
dendritic spot on the second antenna, red spots on the dorsal surface of the posterior 
edge of the third, fourth, and fifth abdominal somites on the median line; red spots 
on the ventral surface of the first, second, and third at the bases of the spines; a red 
and a brown spot at the base of the spine on the fifth ; a brown spot at the base of the 
spine on the sixth, and a red spot on the base of the swimmeret. The anal spots are 
large and bright-red. 
On September 20th I found several specimens of the stage which has just been 
described. Fig. 79 was made from one of them, which was then placed in a glass of 
water by itself, and the next day it was found to be moulting. In the evening 
the moult was found to be finished, and the larva was swimming actively. The 
drawing given in fig. 84 was made from it without injuring it, and later stages were also 
drawn from the same specimen. 
The larva, xoo'o i nc ^ l° n g> has undergone very great change, and although it is an 
Acanthosoma, it presents many important differences from both Lucifer and Sergestes. 
The abdomen has lengthened so that the carapace makes less than one-third the 
total length of the body, and the dorsal and postero-lateral spines have disappeared. 
The abdominal spines stand out from the body, and the swimmerets have become 
the chief locomotor organs. The spine has disappeared from the labrum ; the two 
pairs of antennae have changed from the larval to the adult form ; the endopodite of the 
fourth pereiopod, and the first three pairs of pleopods are represented by long buds. 
MDCCCLXXXII. p 
