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IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
axis of support. The dorsal surface of each scale bears a trace 
of a delicate diagonal pattern. 
Extending forward from the antero-ventral side of the cephalic 
region are two long subcylindrical processes which are broken off 
anteriorly and somewhat swollen near their proximal ends. The 
part of the left member which is preserved has a length of 17 
mm. and its greatest diameter (dorso-ventral) is 5 mm. Their 
surfaces are polished and punctate. Whether these appendages 
represent the first joints of the antennas, -segments of extremely 
large maxillipeds, or the first (or second) pair of proximal seg- 
ments of the first pair of pereiopods the writer is unable to de- 
termine. From their comparatively large size it is probable 
that they are parts of the first pair of pereiopods. Compare, for 
example, the first pair of pereiopods of the modern form Sabinea 
princeps Smith. 6 The remaining thoracic appendages are rep- 
resented by their proximal segments only and these are pre- 
served so poorly and in such a way that' the number can not be 
determined with accuracy. One of them has a length of 4 mm. 
and a diameter of 2 mm. ; others are larger but less well defined. 
On the ventral surface near the posterior end there is exposed 
a fragment which may be a part of an abdominal pleura or a 
part of the telson that may have become impressed on the under 
side of the thorax while in a flexed position. The hardness of 
the matrix makes it difficult to learn its exact character. 
Measurements : Total length of the specimen, 5 cm. ; dorsal 
length of the cephalo-thorax, 32 mm. ; greatest width, 12 mm. ; 
height of carapace, 13 mm. ; distance of antero -lateral spine from 
the rostral spine 7 mm. ; greatest distance across the base of 
antennal scales, 8 mm. 
This specimen agrees with the genus Palaeopalaemon, Whit- 
field, in that the cephalo-thorax is narrow and shrimplike as w T ell 
as keeled on the back and sides but it differs from it in being 
rostrate. The appendages which Whitfield has called antennae 
are here considered as parts of the first pair of pereiopods. The 
presence of a larger number of sulci and carinae and of a right 
and left spine as well as the antennal scales further differentiate 
our specimen from P. newberryi. Indeed, the characters just 
pointed out are suggestive of the modern family Crangonidae 
6 For figure see Bull. Mus. Comp. Zool., Vol. XXIV, No. XVII, p. 38, pi. 
VIII, fig. 1, Cambridge, 1893, 
