554 
J. S. KINGSLEY. 
animal is concerned I can vouch for the accuracy of his 
account. 
In regard to the eighth point of Dr. Packard’s paper, it will 
at once be recalled that the gills in the Crustacea are formed 
on several distinct plans, and an effort to homologise those 
for instance, of forms so closely related as the Lobster and 
Squilla is not easily carried out. I regard the gills of 
Limulus, like those of Apus, as derived from some ancestral 
form with expanded and flattened appendages, which exposed a 
large surface to the water and hence became largely the seat 
of respiration. With a thickening of the cuticle and increase 
in size, the necessity for increased respiratory surface led in 
Limulus to the formation of outgrowths (gill-lamellae) from 
these appendages just as occurs (though not from the same 
reason) in the individual to-day. The not very plainly marked 
biramous character of the abdominal appendages of Limulus is 
an ancestral feature which may have been lost in the Arachnid 
stems from the early change which they undergo. Nothing 
approaching a biramous condition is found in the six cephalo- 
thoracic members of either spiders 1 or horseshoe crabs except 
in^tlm sixth pair of the latter, and to homologise the joints of 
that member with the protopodite, exopodite, endopodite, and 
epipodite of the “ typical ” crustacean limb is a task that I do 
not care to undertake. It seems, on the other hand, to be much 
more like one of the thoracic feet of Apus. 
The condensed metamorphosis mentioned in the fourteenth 
point is, I suppose, another method of saying that the develop- 
ment is direct, for certainly Limulus shows nothing that could 
be regarded in the light of a metamorphosis, and it is just this 
lack of any larval forms which renders it so difficult to decide 
upon the affinities of the forms in question. Had we any 
nauplius or zoea stage the problem would be an easy one to 
solve. As it is the development is direct just as it is in Tetra- 
decapods, Spiders, and many other forms. 
The third of the points is the most difficult to explain. In 
1 Croneberg’s observations on Dendryph antes ('80 ; pi. xvi, fig. It — 16) 
need confirmation. 
