9. Mandibles, same stage, seen from below. The right and left mandibles are not sj-mmetrical. 



10. Fu-st maxilla of left side, same stage, posterior surface. 



11. Second maxiUa of left side, same stage, posterior surface, re, exopodite or rudimentary scaphogiiathite. 



12. First iiiaxilliped of left side, same stage. 



13. Second maxilliped of left side, same stage. Kesembles the first maxilliped, but is much smaller. 



14. Fifth larval stage, or last protozoea stage, raised from the preceding stage, ventral view. xBgir in- long. This 



stiige is Dana's genus Erichthina. The second autenns 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 tlie first (8) are marked by enlargements wliich 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 tlioracic of the typical Decapod, being never developed 

 in Lucifer. Following immediately upon the thirteenth somite is the fii-st abdominal (a^). a*, fourth 

 abdominal somite. The posterior unsegmented portion represents the fiftli and sixth abdominal somites and 

 the telson. 



15. Sixth larval stage, or zoea stage, raised from the preceding stage, ventral side. About illuo i"- long- This 



stage is comparable, so far as the appendages are concerned, witli the Elaphoearis stage of Sergestcs. The 

 third maxillipeds (V'lll) and tlie four following pairs of thoracic appendages (IX-XIl), as well as the swim- 

 merets or appendtiges of the sixth abdominal somite (XIX), are present in a rudimentary sliape 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 thoracic legs in the typical Decapod 

 is w.anting liere and throughout tlie development oi Lucifer, n, abdominal nerve ganglion. 



16. Lateral view of tlie same stage. 



17. Seventh larval stage, or first schizopod stage, viewed from below. About tJ^tj in. long. This stage is Dana's 



genus Scehtina, and represents in a general way the Acanthosoma stage of Sergestcs. Up to this time the 

 larva has swam chiefly by means of the antennse. In this stage the antennae lose their locomotor function, 

 which is now assumed by the long biramous appendages which have developed from the bud-like processes 

 on the thoracic segments of tlie preceding stage. The compound eyes are mounted n]ion short stalks. The 

 second antenna> have become ipiite snnill. The thoracic 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 tliird (last) schizopod stage, lateral view. Between this stage and the one repi'esented 



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 b}' fig. 18 the abdominal appendages ai'e quite large, but 

 still rudimentary. The abdomen is now very much longer in proportion to the carapace than it was in the 

 zoea stages, and flattened from side to side. The outer branch of the second antennae is reduced to a scale. 



19. Second and third maxillipeds (VII, VIII) and the four following appendages of the thorax, left side, seen from 



aliove, same stage. 



20. Young Lvcifcr produced from the moulting of a larva like that shown in fig. 18, lateral view. About i; in. 



long. It now corresponds in many respects with the Mastigopus stage of Sergestcs, 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. Tlie 

 last pair of thoracic feet (XII in fig. 18) have disappeared, together with the outer branches of all the other 

 thoracic appendages, maxillipeds included. The abdominal appendages have their perfect form. II, inner 

 branch or flngellum of .second antenna. IT, outer branch or scale of second antenna. 3, auditory organ in 

 proximal segment of first antenna, y, antennal gland. 



21. Inner surface of mandible of adult. 



22. Second maxilla of adult, r?, inner branch, r ^, outer branch, or scaphognathite. 



