PACKARD. ] DEVELOPMENT OF PHYLLOPODS. Al15. 
well as its fossil allies, and the Eurypterida, the compound eyes are sessile 
and situated on the third segment of the head, and, as we have endeav- 
ored to show in our essay on the development of Limulus polyphemus,} 
the stalked eyes of Decapods do not represent a pair of appendages. 
V.—THE DEVELOPMENT, METAMORPHOSES, AND GENE- 
ALOGY OF PHYLLOPODS. 
I.—THE NAUPLIUS FORM IN THE PHYLLOPODS. 
As introductory to the notes furnished by Dr. Gissler on the develop- 
ment of Apus and Streptocephalus, we will preface his remarks with 
some account of the early phases of different Phyllopods, beginning 
with Limnetis, as worked out by Grube.” 
The young of this genus is a Nauplius of peculiar form, with three 
pairs of appendages, a very large carapace which covers the entire body, 
and the edges of which are serrated. The carapace is larger than in any 
other Phyllopod larva known, and there are two large lateral hornlike 
projections from each side of the head in front of the first pair of ap- 
pendages. The labrum is not especially developed, while in the other 
genera it forms a characteristic feature of Phyllopod nauplii. 
LTimnetis gould has a nauplius of the same general shape as the 
European species, a8 we have received specimens of a similar carapace 
from Hanover, N. H. | 
A quite full account of the development of Limnadia hermanni has 
been given by Le- 
reboullet. Fig. 42 
represents the 
freshly-hatched 
Nauplius, which is 
of very primitive 
form. The first 
pair of antenne 
are in the Nau- 
plius wanting, not 
budding out until 
near adult life. 
The labrum (Ib) Fic. 42.—Nauplius of Limnadia hermanni. ant2, second antenna; md, man- 
is enormous and dible; %, labrum. Much enlarged. After Lereboullet. 
very long. The carapace arises in this genus, as also in Estheria, from 
a point in the head just behind the mandibular segment. Fig. 43 rep- 
resents the larva before the first antenne have begun to grow out. 
The ocellus is still large and performs its functions, while the abdomen 
ends in a pairof uropoda. Thedevelopment of Hstheria, as given in a 
fragmentary way by Joly, shows that the Nauplius differs mainly from 
that of Limnadia in the labrum being three-toothed at the end. 
Fig. 44 represents the freshly hatched larva of Apus cancriformis ; 
the usual three pairs of nauplius-appendages representing the first and 
second antennz, and the mandibles of the adult are present; while the 
ovate body is segmented behind the mandibular segment. 
The first larval stage of Lepidurus, as worked out by Brauer (Tigs. 45, 
46), israther different from that of Apus. The limbs are slenderer, and a 
rudimentary carapace arises on the antennal segments, while the body 
behind is not segmented. 
!Memoirs Boston Soc. Nat. Hist., 1872, Vol. 1, pp. 174, 175. 
?Bemerkungen tiber die Phyllopoden. 
