74 Mr. C. Spence Bate on a new Genus of Macrura. 
which have’ been transferred into the ‘ Challenger’ Report on 
the Crustacea Macrura, p. 112, ‘ryon was probably not blind, 
for the eye-stalks have been found in several specimens.” 
On the other hand, Dr. Woodward, of the British Museum, 
who as a geologist has given much attention to this group of 
Crustacea, says that the eye ‘has never been positively 
determined,” and he has restored a specimen with these organs 
present. I have never seen a specimen, neither, I believe, has 
any ever been found in which the ophthalmus is undoubtedly 
preserved, 
In Eryon Brodiet the orbit is preserved and shown to be 
moderately deep, and the latero-anterior angle is well ad- 
vanced. It isthe same, but in a rather less marked condition, 
in Eryon wilmcotensis, while in Eryon Mooret and Eryon 
crassicheles both orbital notch and antennal angle are reduced 
to a minimum. 
In Archeastacus Willemesti the latero-anterior angle of the 
carapace is so well developed as to produce a well-formed but 
shallow orbital notch in the frontal margin of the carapace in 
position corresponding with those found in the recent genera, 
but less excavate and characteristic. In this unique fossil 
the ophthalmopoda are not preserved, but the form of the orbit 
is suggestive of the existence of such an organ. 
From the Upper Lias of Calvados M. Moriére described * 
a species under the name of Eryon calvadosii, in which the 
orbits for the reception of the organs of vision are well pre- 
served, and the specimen has the appearance of having had the 
ophthalmopoda broken off and retained in the lost matrix. 
If we now turn to the specimen before us we find that the 
organs of vision are present in a peculiar and well-developed 
form. The ophthalmus is projected upon an elongated and 
slender stalk, and is capable of being bent considerably on 
itself; and both articulations possess considerable mobile 
power, so much so that the ophthalmus is capable of being 
bent beneath the frontal margin and hidden from view. But 
although it is not visible when inspected on the dorsal sur- 
face, it is so placed that it is capable of seeing through 
the curved or hollow space that exists on the outer side 
beneath the antero-frontal angle of the carapace; but when 
the animal wills it is capable of being projected forwards, 
and when advanced the peduncles may be seen very much like 
those shown in Eryon Cuviert, as figured by Desmarest 
and shown in our woodcut on page 73. 
The first pair of antenne exhibit a peculiarity at variance 
* Bull. Soc. Linn. de Normand. sér. 3, tom. vii. pp. 1-10, pls, i-iii, 
(1883). 
