502 Progress of American Carcinology in 1879. [July, 
The gastrula mouth soon closed. The first parts of the embryo 
to appear are the labrum, two pairs of antennz, the mandibles 
and the abdomen, the latter very near the former position of the 
gastrula mouth. These parts appear almost simultaneously. Four 
days later both pairs of maxillz and the first pair of maxillipeds 
have hudded; in seven, the two remaining pairs of maxillipeds 
have appeared, all appendages showing a biramose character. 
The growth goes regularly on, the yolk being gradually absorbed, 
the eyes appearing at first as patches of dark pigment,) and when 
the prawn hatches there is a small simple eye at the base of the 
rostrum, the eyes proper are supported on short pedicels, the 
antennulz are simple, the antennz biramose, the future scale 
being much larger than the flagellum, the mandibles at no stage 
possess palpi. The scaphognathite (gill bailer) is in constant 
motion, though no gills are yet present. The three pairs of max- 
illipeds are two-branched, and their basal joints act as jaws, 
reminding one, as Dr. Faxon says, of the manducatory apparatus - 
of Limulus. The ambulatory feet are represented by only two 
pairs of double sacks, the other three being undeveloped. The 
abdomen is six-jointed and without a trace of appendages. A 
moult brings two more ambulatory feet, and with the next exuvia- 
tion the second antennal flagellum appears and the abdomen has 
seven joints, the sixth with its appendages appearing. After 
another moult two of the basal rostra®teeth appear, the third pair 
of ambulatory feet acquire a natatory character, and the fourth 
and fifth pairs as well as the abdominal feet have budded. With 
two more moults the animal has acquired all its swimming feet, 
but differs from the Schizopoda (Mysis) in having the last pair 
simple, the exopodite being absent. In two or three more exuvia- 
tions the exopodites are reduced to simple styles, and after a 
few more, the shrimp, then about eight millimetres long, acquires 
essentially the characters of the adult. Rostral teeth, however, 
continue to be added with growth. 
Succeeding this account, summarized above, Dr. Faxon gives 
a critical review of the literature of the development of Palemon, 
and we think him right in disagreement with Mr. Spence Bate 
regarding the homologies of the three pairs of appendages which 
appear first in the Crustacean embryo. 
1 I would here quote the foot-note on p. 308: “The development of the eye cer- 
tainly lends no countenance to the idea that its stalk is an appendage homologous 
wita the antennz, ete.” 
