130 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 
“Generically, it is separated from Gampsonyx, figures of which (cuts C and D) we have added 
for comparison, not only in the nature of its caudal appendages, but in the more important char- 
acter of having its thoracic legs simple, and not bifid, as in the Schizopoda.” 
ee rGaaes 
(ea Jeane 
x | ~ 
= SS QOVyyer \ 
eR | 
\ sh 
Fic. 1.—Gampsonyx fimbriatus. After Jordan and von Meyer. From Meek and Worthen. 
We will now describe in detail Paleocaris typus, restoring it so far as possible in our description 
from the specimens received from Messrs. Lacoe and Carr, amounting in all to about a dozen, of 
which ten were kindly loaned by Mr. Lacoe. Dr. Kingsley has also obligingly drawn a restoration 
of the fossil from the specimens sent him for the purpose. There are no traces of a carapace, but 
the head is plainly distinet from the rest of the body. It is rounded in front, with no traces in my 
specimens of a rostrum, and is apparently composed of two segments. The body, seen sidewise, is 
suddenly arched or bent at the articulation of the thoracic and abdominal regions, as in stoma. 
pods and shrimps, and of the usual proportions. All the segments behind the head are free, and 
are fourteen (seven of which are abdominal) in number, counting the telson as one. There are 
thus sixteen segments, the head composed of two, the thorax of seven, and the abdomen of seven. 
The body thus has apparently the same number of thoracic and abdominal segments as in the 
existing Stomapoda. It is probable that the head of Palwocaris is composed of the same number 
of segments as in the Schizopoda, but as the mouth parts have not been preserved, this point must 
remain undetermined. The thorax, in its general shape, as seen from above, is of the normal shape, 
as seen in existing Stomapoda. The abdomen is much narrower than the thorax, with the basal 
segments short, and the penultimate one longer than broad, widening out a little on the hind margin, 
and excavated behind to receive the base of the telson. 
The first antenne are about one-half as long as the body, with the scape long and slender, 
three-jointed (unless what I regard as the basal joint consists, as appearances suggest, of two); 
first joint long and slender; second, as thick but only one-halfas long as the first; third, moder- 
ately long, considerably longer than the second; flagella nearly equal in size, long and slender. 
The second antenne with the scape three-jointed, the basal joint long; second and third, of nearly 
the same size and length; flagellum thick at base, long and slender, entire antenna nearly half as 
long as the body of the animal. 
Of the thoracic feet, six pairs can be detected, while in front of the first pair are two other 
appendages like thelegs, but whether they are gnathopods, like those of other Schizopoda, or thoracic 
feet, it is difficult to judge. Each thoracic foot is long and slender, the three distal joints forming 
the greater part of the limb. The terminal (seventh ?) joint is very long and slender, and probably 
ends in @ single claw. The penultimate joint is about two-thirds as long as the terminal. It is 
thickened towards the end, and is perhaps a little shorter than the third joint from the end. 
The endopodites* are distinetly preserved ; those on the last four pairs of legs are long, narrow, 
lanceolate-oval, acute at the end, each side of the endopodites being alike, 7. ¢., one not being more 
convex than the other. If extended, the endopodite would reach out to near the middle of the 
terminal joint of the limb. I think I can detect eight pairs of endopodites—six at least— one on 
each thoracic leg and one on each of the gnathopods, if such they are. This would tend-to show 
that the first two appendages behind the head are true gnathopods, like those of existing Schizo- 
pods, especially Petalophthalmus. 
There are traces of a pair of abdominal legs to each of the seven segments. To the rather 
“Thad regarded these appendages as breeding lamellw, but Dr. Kingsley suggests that they are endopodites, and 
though the joints are very indistinct, I am disposed to accept his correction, and will speak of them as endopodites. 
We should, on general grounds, regard them as endopodites 
