. Mandibles, same stage, seen from below. The right and left mandibles are not symmetrical. 
. First maxilla of left side, same stage, posterior surface. 
. Second maxilla of left side, same stage, posterior surface. re, exopodite or rudimentary scaphognathite. 
. First maxilliped of left side, same stage. 
. Second maxilliped of left side, same stage. Resembles the first maxilliped, but is much smaller. 
. Fifth larval stage, or last protozoéa stage, raised from the preceding stage, ventral view. y{>in. long. This 
stage is Dana’s genus Hrichthina. The second antenne are still the chief organs of locomotion. The hind- 
body has increased in length, and now consists of nine free somites and an unsegmented posterior portion. 
The outer edges of the first (8) are marked by enlargements which appear to be rudiments of the third 
maxillipeds. 12, twelfth somite (counting the first antenna as the appendage of the first somite). This is 
the posterior thoracic somite, the thirteenth or last thoracic of the typical Decapod, being never developed 
in Lucifer. Following immediately upon the thirteenth somite is the first abdominal (a1). a‘, fourth 
abdominal somite. The posterior unsegmented portion represents the fifth and sixth abdominal somites and 
the telson. 
15. Sixth larval stage, or zoéa stage, raised from the preceding stage, ventral side. About 7$§> in. long. This 
stage is comparable, so far as the appendages are concerned, with the Elaphocaris stage of Sergestes. The 
third maxillipeds (VIII) and the four following pairs of thoracic appendages (IX—XII), as well as the swim- 
merets or appendages of the sixth abdominal somite (XIX), are present in a rudimentary shape as bilobed 
buds. All the somites of the abdomen are now well marked except the sixth, which is not yet clearly 
separated from the telson. The somite which carries the last pair of thoracie legs in the typical Decapod 
is wanting here and throughout the development of Lucifer. mn, abdominal nerve ganglion. 
16. Lateral view of the same stage. 
17. Seventh larval stage, or first schizopod stage, viewed from below. About 73§> in. long. This stage is Dana’s 
genus Sceletina, and represents in a general way the Acanthosoma stage of Sergestes. Up to this time the 
larva has swam chiefly by means of the antenne. In this stage the antenne lose their locomotor function, 
which is now assumed by the long biramous appendages which have developed from the bud-like processes 
on the thoracie segments of the preceding stage. The compound eyes are mounted upon short stalks. The 
second antenne have become quite small. The thoracie appendages (VI—XII) are much alike in structure 
and with the telson and swimmerets (XIX) serve to propel the animal through the water. The telson is 
separated from the sixth abdominal somite. 
18. Ninth larval stage, or third (last) schizopod stage, lateral view. Between this stage and the one represented 
by fig. 17 one intervenes similar to fig. 17, but a little larger and furnished with abdominal appendages in 
the form of small buds. In the stage represented by fig. 18 the abdominal appendages are quite large, but 
still rudimentary. The abdomen is now very much longer in proportion to the carapace than it was in the 
zoéa stages, and flattened from side to side. The outer branch of the second antenne is reduced to a scale. 
19. Second and third maxillipeds (VII, VIII) and the four following appendages of the thorax, left side, seen from 
above, same stage. 
20. Young Lucifer produced from the moulting of a larva like that shown in fig. 18, lateral view. About 4 in. 
2 
2 
ale 
9 
long. It now corresponds in many respects with the Mastigopus stage of Sergestes, and has a form essentially 
like that of the adult Lucifer. The flagellum of the first antenna, however, is much shorter than in the 
adult, and the neck of the carapace is short. The thorax is relatively smaller than in the last stage. The 
last pair of thoracic feet (XII in fig. 18) have disappeared, together with the outer branches of all the other 
thoracie appendages, maxillipeds included. The abdominal appendages have their perfect form. II, inner 
branch or flagellum of second antenna. II’, outer branch or scale of second antenna. 8, auditory organ in 
proximal segment of first antenna. -y, antennal gland. 
Inner surface of mandible of adult. 
2. Second maxilla of adult. 77, inner branch. re, outer branch, or scaphognathite. 
