ON THE ANASPIDACEA, LIVING AND FOSSIL. 519 
pides (text-fig. 3), as being. the best known, will receive 
first attention. The first thoracic limb isunknown. The second 
limb was apparently composed of three or four small basal 
joints and an expanded segment below the ‘knee,’ and 
probably three segments above the “knee.” Hxcept that no 
exopodite can be seen, it appears to have agreed with the 
corresponding limb of the living Anaspidacea. ‘I'he succeeding 
thoracic limbs agree very perfectly with those of living forms. 
There was a two-jointed protopodite from which sprang a 
flagellate exopodite and a stout five-jointed endopodite, three 
of these segments being distal to the knee as in living Anas- 
pidacea. In the last two thoracic limbs it is impossible to 
make out an exopodite, and this is again in agreement with 
the structure of the living genera. In the most perfectly 
preserved limbs it is only possible to make out seven segments 
in each limb, so that the fusion of the second and third segments 
may have already taken place in this form, but it iS more 
probable that there were eight segments and that the con- 
dition of preservation does not permit us to see them all. 
In Gampsonyx and Palewocaris we can only obtain a 
vague idea of the structure of the limbs. In the former the 
second limb was apparently of a raptorial nature, being 
greatly enlarged and furnished with prominent spines ; the 
succeeding limbs one can only describe vaguely as biramous. 
In Paleocaris, if we can trust the diagrammatic reconstruc- 
tion of Packard (text-fig. 56), the last six thoracic limbs were 
all similar and all biramous, with stout endopodites and slender 
exopodites. 
In Gasocaris the endopodites are all similar and stoutly 
built, but Fritsch denies the presence of exopodites at all, a 
denial about which we may suspend our judgment, owing to 
the delicacy of the exopodites in the Anaspidacea and the 
difficulty of making them out even in the best preserved 
fossils. 
The abdominal appendages, 1-5 in the females of 
Anaspidesand Paranaspides, have alla very similar struc- 
ture, except the fifth, which is without an endopodite. The 
VoL. 53, PART 3.—NEW SERIES. 36 
