MUSEUM OF COMPARATIVE ZOOLOGY. 255 
the body. Its further course was not determined. The two posterior vessels 
correspond to the superior abdominal and sternal arteries of the adult. I was 
unable to discover any vessels answering to the antennary and hepatic arteries 
of the adult. 
After issuing from the ends of the arteries, the blood may be seen coursing 
through the cavities of the body back to the heart. Two of these currents 
are evident in the abdomen, one above, and the other below, the abdominal 
artery. The venous blood in the cephalo-thorax streams back from the head 
along the border of the carapace and upward to the heart. No traces of gills 
exist at this stage. The blood is aérated in a great measure, probably, through 
the thin walls of the carapace, currents of water being kept up, as in the gill- 
bearing adult, by the constant motion of the scaphognathite of the second pair 
of maxilla. 
The integument is nearly colorless and transparent, with a few blotches of 
bright red pigment. The largest of the pigment-spots are, one on the lower 
side just back of the mouth, two on the carapace at the points where the 
lateral spines subsequently appear, and two on the telson (one on either side 
of the anal opening). Beside these there are a few smaller specks of pigment 
on the carapace and on the second, third, and fourth segments of the abdomen. 
It will be seen, from the foregoing description and from the figures, that we 
have the same stage of the larva as that noticed by Fritz Müller on the coast 
of Brazil in the case of Hippa emerita. Of this a brief notice and an unsatis- 
factory figure are given in his work * Für Darwin.” * Up to the time of 
Smith’s observations this was all there was known of the developmental his- 
tory of Hippa. The notice is very brief: “The zoéa of the Tatuira [Hippa 
emerita] (Fig. 25) also appears to differ but little from those of the true crabs, 
which it likewise resembles in its mode of locomotion. The carapace possesses 
only a short, broad frontal process; the posterior margin of the tail is edged 
with numerous short sete.” 
Professor Smith says: “ Very nearly fully developed embryos, when. re- 
moved from the egg, were found to possess all the normal articulated appen- 
dages of the fully formed zoëæ, but there was no appearance of lateral spines 
upon. the carapax, and the rostrum was broad and obtuse. In this stage the 
embryo agrees almost perfectly with the figure of the zoéa of Hippa emerita 
from the coast of Brazil, given by Fritz Müller in his work entitled ‘ Für Dar- 
win.’ The difference between the embryo in this stage and the second zoéa- 
stage [i. e. the stage presumed to be the second] (Plate XLV. Fig. 1), in which 
the rostrum and lateral spines are enormously developed, suggests the pos- 
sibility that Müller had observed only imperfectly developed young zoów in 
which the rostrum and lateral spines were not expanded. It seems scarcely 
probable that such a difference could exist between the first stage of the 
zoéa, when the veiling membrane, in which, on first escaping from the egg, the 
* Für Darwin, 1864. English Translation by W. S. Dallas, pp. 53, 54 ; Fig. 25. 
1869. 
