402 Dr. H. Woodward—On a Fossil Schizopod Crustacean. 
termination of a large abdomen bent upon itself with the telson and 
uropods more or less flattened and crushed.” 
Professor Huxley then compares Pyyocephalus with MMysis, the 
‘opossum-shrimp’ of our own seas:—‘‘In Mysis, as in Pygocephalus, 
the abdomen is very large, as compared with the thorax, and the 
carapace is short and delicate. The antennules present two sub- 
cylindrical basal joints; the antenne have two large basal joints 
giving attachment to a large scale externally and superiorly, while 
internally the fusiform base of the internal division of the antenne is 
formed by three joints, with the last of which a very long multi- 
articulate filament is continuous” (see Plate XVIII). 
‘“There are seven pairs of conspicuous thoracic members in Dysis, 
the first pair of thoracic appendages being smaller than the others, 
and applied against the mouth; so, also, there are seven pairs of 
appendages in Pygocephalus,” but the oral appendages in the fossil 
cannot be accurately determined. 
“In Mysis, again, the thoracic limbs are short and feeble, and 
consist of two parts, an endopodite and exopodite, the latter being 
terminated by a many-jointed filament. They present the same 
peculiarities in Pygocephalus” (Pl. XVIII, Figs. 2, 9). 
‘““In Mysis the sterna of the thoracic somites are well developed, 
and gradually increase in width from before backwards; so do those of 
Pygocephalus.” 
“The abdomen in Pygocephalus is much thicker and stronger in 
proportion than is that of Mysis’’; and as seen from the drawings by 
Mr. Searle of the later specimens obtained, the telson, together 
with the three-jointed and paired uropods, on either side, differ 
greatly in form from those of Mysis, being far wider, more nearly 
resembling some of the Coal-measure Palemonide figured by 
Dr. B. N. Peach, F.R.S.! This agrees with our experience con- 
cerning all these earlier forms of Crustacea, that they are less 
specialized in structure than are those of our modern times. 
Huxley concludes that Pygocephalus is either a lowly form of 
Decapod or one of the Stomapoda, and he adds in a note, ‘the 
Schizopoda, including J/ysis, are not essentially different from the 
Decapoda.”’ 
The result of our examination of the fine series of specimens of the 
male of Pygocephalus, obtained since 1857 for the British Museum 
(Natural History), tends not only to expand and perfect Professor 
Huxley’s original description, but to prove the great accuracy of his 
observations of fifty years ago. 
The additional specimens lately received from Mr. Herbert Hughes, 
obtained from the same bed of clay-ironstone nodules at Coseley, near 
Dudley, which formerly proved so prolific under the labours of the 
late Mr. Henry Johnson, have yielded clear evidence of the female of 
Pygocephalus. Those which are illustrated upon our Pl. XVIII, 
Figs. 5 and 6 show most distinctly the presence of a brood-pouch or 
marsupium on the ventral aspect of the thorax. Such structures are 
well known in many recent Crustacea, but have not hitherto been 
preserved in any fossil form. 
1 See Trans. Roy. Soc. Edinb., vol. xxx (1888), pls. 8-10. 
a 
