86 B. N. PEACH ON SOME NEW CRUSTACEANS FROM THE 
Cephalic Appendages.—No eyes have with certainty been observed. 
Antennules two, each made up of a long propodite of three or four cylindrical 
joints supporting two many-jointed whips, the tips of which have not been 
preserved, so that nothing can be said as to whether the outer or inner be the 
longer. The antenne consist of a shorter and thicker propodite, which 
supports a rounded basal scale and a many-jointed flagellum, which is much 
stouter than those of the antennules, and probably extended much beyond 
them, though only the bases are now preserved. The other cephalic ap- 
pendages have not been observed. 
Thorax and abdomen are composed of similar segments, which are twelve 
in number; those of the thorax not having the terga and pleura soldered to- 
gether nor confluent with the carapace. All are free to move on each other, 
and are composed exactly like a typical abdominal segment of a decapod. 
Each ring exhibits a tergum flanked by pleurz, which are marked off from it 
by a folding in of the test. These grooves are continued backwards from those 
already mentioned as occurring on the carapace to the anterior lateral margins 
of the telson. The pleure are poimted, and directed backwards. The body 
tapers gradually from the second thoracic segment. The three last abdominal 
segments are ornamented on the terga with two ridges, situated just within the 
grooves, and these are continued on the telson. No appendages have been with 
any certainty seen on any of the above segments, except on the last abdominal 
one, which supports a joint at each posterior angle. To each of these are 
attached a pair of broadened swimming flaps, the strengthening portions of 
which are usually alone preserved as flattened spines; those of the exopodite 
being the longer and more pronounced. The telson is shield-shaped, broad at 
the base and tapering almost to a point, and then suddenly broadening out 
spoon-fashion at the tip. At least one pair of small spines are attached to it 
immediately above its narrowest part. The tail is in character quite that of a 
macrurous decapod. The test is ornamented all over with slight corrugations, 
which, along with a metallic lustre the fossil usually presents, makes the 
slightest fragment recognisable. 
Observations.—This species was found by A. Macconocutz at the locality on 
the Esk where the other fossils were procured, and from which about thirty speci- 
mens have been obtained. From the nature of the matrix, which is a sandy and 
calcareous shale, and the fact that the test of even these tiny creatures are infested 
with innumerable calculi of the character already described, they cannot be 
studied as narrowly as might be wished. For instance, although in most of the 
specimens there occur small oblong bosses just in the place where their eyes 
should be, were they decapods, figs. 10-10d, yet the facets of the cornea have been 
looked for in vain. This is unfortunate, as it prevents one from saying with 
certainty that these are the eyes, though there is a strong presumption in favour 
