ON THE FOSSIL PHYLLOPODA OF THE PALHOZOIC ROCKS. 353 
family distinction, of which, for the present, we do not propose to estimate 
the value. 
22. PHYSOCARIS VESICA, Salter. 
1860. Ceratiocaris (Physocaris) vesica, Salter. ‘Ann. Mag. N. H.’ ser. 3, vol. v. 
p. 159, woodcut fig. 
1865. Ceratiocaris (Physocaris) vesica, Salter and H. Woodward. ‘Catal. Chart. 
Foss. Crust.’ p. 17, fig. 8. 
1867. Ceratiocaris vesica, Salter. In ‘Siluria,’ 3rd (4th) edit. p. 517. 
1877. Ceratiocaris (Physocaris) vesica,H. Woodward. ‘Cat. Brit. Foss. Crust.’ p. 72. 
1878. Ceratiocaris vesica, Huxley and Etheridge. ‘Cat. C. S. Foss.’ p. 142. 
Of this curious fossil Phyllopod, described carefully by Mr. Salter in 
1860, only one specimen is known—namely, ‘Ludlow Museum U.’ It 
differs slightly from Mr. Salter’s figure, being larger, and showing an 
appearance of having been probably broken away to a little extent just 
above the front, so as to leave a notch and angle, which constitute the 
prominence in the woodcut figure. If continued over this notch the out- 
line of the shell would possibly be that of a broad oval; whereas now it 
is broadly and obliquely pyriform (25 x2%0mm.). The relative position 
_ of the animal is supposed to be indicated by the telson occupying the 
upper part of the abdominal appendages attached to the fossil. There 
are 8-9 segments in the abdomen, which appears to come out from the 
lower and hinder quarter of the carapace, and is very slender near its 
origin, but higher at its ultimate segment (5mm. long); altogether 
30mm. The telson itself is 11mm. long. One lateral spine (stylet), 
7mm., is present. The whole animal is about two inches long. 
It was collected by the late Mr. Salwey in the Lower Ludlow at 
Leintwardine, and Mr. Salter at first registered it as Ceratiocaris inflata. 
23. AcantHocaris, B. N. Peach, 
In the ‘Transact. R. Soc. Edinburgh,’ vol. xxx. Part I. for 1880-1 
(1882) Mr. B. N. Peach gave a memoir ‘On some New Crustaceans 
from the Lower Carboniferous Rocks of Eskdale and Liddesdale; and in 
Part II. for 1881-2 (1883) his ‘ Further Researches among the Crustacea 
and Arachnida of the Carboniferous Rocks of the Scottish Border.’ In 
the first memoir he described and figured his new Ceratiocaris scorpioides 
(p. 73, pl. 7, figs. 1-1f), and C. elongatus, p. 74, pl. 7, figs. 2-2f. In 
1883 he instituted a new genus, Acanthocaris, for these curious Cuma-like 
forms, and added a new species, A. attenuatus (p. 512, pl. 28, figs. 1-le). 
Acanthocaris has its body much longer than the carapace, which is small, 
with a blunt snout-like projection in front and rounded postero-ventral 
side-lobes behind. Two denticulated jaws occur within the carapace 
near the antero-ventral margin. The total length of the animal from 
1 to 2} inches. It has a much smaller carapace and longer abdomen 
than Ceratiocaris, aud the form and structure of the carapace, and the 
relative size and shape of the segments, are very distinctive. Mr. Peach 
thus describes the genus :— 
‘Carapace small and not hinged, produced anteriorly into a blunt 
snout, and posteriorly into rounded lobes. Body fusiform and long, 
composed of numerous segments which increase in length backwards, the 
Seven posterior ones being uncovered by the carapace. Third segment 
from tail tumid and notched on its ventral surface. Telson long and 
spiniform, and flanked on each side by a rudimentary spinelet. Test 
rae slightly wrinkled, but not striated longitudinally.’ 
. AA 
