136 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 
details, which he has so faithfully drawn. I am inclined to think that the body was actually 
broader than Dr. Kingsley has drawn it, and that tlie lateral spines of the carapace were visible 
from above; but I leave it as an open question. 
The carapace is of the same length as the urosome (abdomen) or slightly longer, being from 
two-thirds to three-fourths as wide as itis long. Itis very thin and delicate, and many specimens 
have none. The sides are regularly curved, and unarmed behind the middle, but on the anterior 
third are seven distinet, sharp lateral spines, the seventh being three times as large as the others 
and situated on the anterior outer angle of the carapace. I cannot with certainty distinguish any 
spines between this last-mentioned spine and the rostruin.* Casts of the latter are distinctly seen 
in two specimens (Lacoe’s 200pp and 200mm) to be small, triangular, short, and acute. The 
rostrum itself is pretty well preserved in one specimen (Mr. Lacoe’s No. 200)). It is rather long, 
stout, strong, acute, situated between the first antenna, and extending as far as the middle of the 
third joint of the scape of the latter. In another specimen (Lacoe’s 20000, 200nn) the rostrum is 
fairly well preserved ; it is long and slender, and about half as long as the carapace; also as long 
as the abdomen is wide in its narrowest part. 
In only a single specimen is a side view of an apparently folded carapace preserved. The 
entire rostrum is long and straight, slender and acute, originating in the anterior third of the 
carapace, the entire rostrum being about half as long as the carapace itself. (Pl. VII, figs. 3. 3a.) 
Along the sides are numerous sharp spines. Whether there was, as in the other form (A. 
grossarti), a series of dorsal spines our specimens do not distinetly show. Behind the base of the 
rostrum a median ridge extends to the posterior edge of the carapace. The lower edge of the 
carapace is serrate on the anterior third, as in all the other specimens. On the surface of the 
carapace an apparently false or superficial suture passes out laterally from the anterior third, and 
another impressed line, better marked, from the posterior third, extending half-way to the edge 
of the carapace. The surface of the carapace is seen to be finely shagreened, but scarcely tuber- 
culated, as in the European A. grossarti. 
Of eyes no traces are visible in any of the specimens except one, and Iam inclined to the 
opinion that they were either wanting or very small, and concealed under the front edge of the 
carapace. At the same time it should be observed that in none of the fossil macrurous Crustacea 
from the Carboniferous are the eyes preserved. It may also be borne in mind that in the deep- 
sea Pentacheles sculptus 8 vith no corneal area was to be detected, and in Willemesia and the fossil 
Eryoniscus the eyes are entirely wanting.t So far as we can decide, the front edge of the carapace 
is not excavated at ‘.e point where we should look for eyes or eye-stalks, but, on the contrary, 
seems to be quite regularly convex. Still, additional specimens are needed to clear up the exact 
nature of the front edge of the carapace. 
In most of the specimens the thin, delicate carapace has not been preserved. When it is 
absent the five thoracic segments are distinetly marked, of about the same length. In front of 
these are three cephalic segments, making eight segments in all apparent in some specimens. 
The first antenne are large and long; the scape three-jointed, first joint long, the second about 
one-half as long as the first and of about the same width; third joint a little longer, but smaller, 
than the second; the two flagella are a little longer than the scape, the inner one about half as 
thick and evidently only half as long as the outer one. (Lacoe, No. 2007.) 
The second antenne are, with the scape, considerably stouter than those of the first pair; first 
joint short and stout, but longer than broad; second very short, oblique at the end, and consid- 
erably shorter than the third joint, which is about as long as thick; the flagellum is very long and 
slender, multiarticulate, at least as long as the carapace, and directed back ward, as in Pentacheles; 
there is an antennal scale present, but its outlines are very indistinct. 
The five pairs of legs are preserved (Nos. 200pp, 200"); they are all of nearly equal size, the 
first pair apparently being no larger than tie others, in this respect differing from Galathea and the 
existing Galatheidea, Of the first pair of limbs there are in one specimen (200d) traces of nearly 
* Dr. Kingsley has, however, detected a spine at this point and inserted it in his drawings, as seen in the plate, 
t After this paper was written the specimens were sent to Dr. Kingsley to be drawn; among them the specimen 
with traces of an eye. He has drawn in the eye; and on examining the specimen again, I think that he is right in 
representing the eyes. It was apparently large and well developed. 
