[523] INVERTEBRATE ANIMALS OF VINEYARD SOUND, ETC. 229 
is clearly defined and extends in a gentle curve from the middle of the 
eye to the posterior border of the embryo. ‘This margin of the cara- 
pax is marked with dendritic spots Fig. 4.* 
of red pigment. The whole dorsal 
portion, fully one-half the embryo, 
is still oceupied by the unabsorbed 
portion of the yolk, (a, a,) of which 
the lower margin, represented in the 
figure by a dotted line, extends from 
close above the eye in a curve near- 
ly parallel with the lower margin 
of the carapax, but with a sharp in- 
dentation a little way behind the 
eye. The eyes (c) are large, nearly 
round, not entirely separated from 
the surrounding tissues,and with a 
central portion of black pigment. 
The antennule (d) are simple, sack- 
like appendages, arising from just beneath the eyes, with the terminal 
portion turned backward and marked with several large dendritic spots 
of red pigment. The antenne (e) are but little larger than the anten- 
nule and are sack-like and without articulations, but the scale and 
flagellum are separated and bent backward, the scale being represented 
by the large and somewhat expanded lobe, and the flagellum by a 
shorter and slender lobe which arises from near the base of the scale. 
The mandibles, both pairs of maxille, and the first and second pairs of 
maxillipeds are not sufficiently developed to be seen without removing the 
antenne and the edge of the earapax, and are only represented by several 
small lobes, of which the anterior, apparently representing the mandi- 
bles, are distinctly defined, while those that follow are much smaller, 
indistinet, and confused. The first and second maxillipeds are each re- 
presented by a small lobe divided at the extremity. The external max- 
illipeds (f) are well developed and almost exactly like the posterior 
cephalothoracic legs. Both the branches are simple and sack-like, the 
main branch, or endognathus,t much larger and slightly longer than the 
No, 610 
*Embryo, some time before hatching, removed from the external envelope and 
shown in a side view enlarged twenty diameters; a, a, dark-green yolk mass still 
unabsorbed ; }, lateral margin of the carapax marked with many dendritic spots of red 
pigment; c, eye; d, antennula; e, antenna; f, external maxilliped; g, great cheliped 
which forms the big claw of the adult; h, outer swimming branch or exopodus of the 
same; i, the four ambulatory legs with their exopodal branches ; k, intestine; /, heart; 
m, bilobed tail seen edgewise. [Drawn by 8. I. Smith. ] 
t To prevent confusion, the terms here used are those proposed by Milne Edwards to 
designate the different branches of the cephalothoracic appendages: endopodus, for the 
main branch of a leg ; exopodus, for the accessory branch, (a in fig. D, Plate IX ;) epipo- 
dus, for the flabelliform appendage, (b ;) and endognathus, exognathus, and epignathus, for 
the corresponding branches of the mouth organs. 
