8 Crust. 
CRUSTACEA. 
spines entirely lost, telson a simple plate, carapace vertically 
flattened, all appendages profoundly modified. 
First Crab Stage, three teeth on each side of carapace, anchylosed 
segment for fifth walking leg. 
Further, he follows each appendage, from the eye and antennula to 
the abdominal appendages, from their first appearance until their last 
transformation. It was impossible to raise any one crab from the egg 
to the adult stage ; specimens were raised from the egg to the second 
Zoea stage, and the moults observed from stage to stage throughout. As, 
however, many moults do not alter the form of the Zoea, the number of 
them could not be determined exactly. Stub. Biol. Lab. Johns Hopkins 
Univ. ii. No. 4, pp. 411-426, pis. xxx.-xxxiii. 
W. K. Brooks has very successfully studied the development of 
Lucifer , concerning which only a few suggestions by the late R. von 
Willemoes-Suhm have been recorded. He describes first the genital organs 
of the adult, then the eggs and their segmentation, which is simplified by 
the restriction of the food-material to a single one of the cells of the 
segmenting egg ; this the author thinks to be a secondary change, not a 
primitive feature. The larva is hatched in the form of Nauplius, and 
passes thence successively through a second Nauplius or Meta-nauplius 
stage, preparatory to the following : — Three Proto-zoea stages, the third 
of which is Dana’s Erichthina } a Zoea stage, corresponding to the Ela - 
phocaris form of Sergestes, and three Schizopod stages, the first of which 
corresponds to the Acanthosoma , the third to the Mastigopus stages of 
Sergestes , before reaching the adult form. In the last, the male is one 
step more advanced than the female. All these stages are fully described 
and figured, and the development of the single pairs of appendages is 
followed through all. The Proto-zoea and Zoea forms make an unbroken 
series, but there is a remarkable change in profound structural points be- 
tween the Meta-nauplius and the first Proto-zoea, and between the Zoea 
and the Schizopod form. Neglecting the features which, at the end of 
each stage, make their appearance as preparation for the next, the author 
characterizes these more important steps of development as follows 
(p. 91) 
1. Nauplius. Three pairs of locomotor appendages, both pairs of 
antenme and mandibles ; a large labrum without a spine ; cara- 
pace and telson absent ; an ocellus, no compound eye. 
2. Proto-zoea. Antennas as in Nauplius ; mandible reduced to a 
cutting plate ; two pairs of biramous maxillae, with scaphogna- 
thites and two pairs of biramous maxillipeds ; hind body long, 
with a flat telson ; labrum with a spine ; carapace large, with 
a rostrum, a median dorsal and two lateral posterior spines, its 
free edges reach down beyond the basal joints of the append- 
ages. An ocellus, no stalked eye. In this and in the preceding 
stage, locomotion consists of short jerking leaps, as in many 
Entomostraca , the two pairs of antennae being the chief organs 
employed. 
3. Schizopod stages. Both pairs of antennae reduced to the per- 
manent form; all the mouth parts and four pairs of thoracic 
