552 
J. S. KINGSLEY. 
bered that Limulus differs from the Tracheates, including the 
Arachnids, (1) in having no tracheae, (2) no spiracles, and (3) 
no Malpighian tubes. It differs from the Arachnids in these 
characters, also (4) in having compound eyes, (5) no functional 
mandibles or maxillae, (6) the legs not terminating, as generally 
the case in Tracheates, in a pair of minute claws, while (7) its 
brain does not, as in the Arachnida, supply both eyes and the 
first cephalic appendages. On the other hand, Limulus agrees 
with the Crustacea (8) in being aquatic (9) and breathing by 
external gills attached to several pairs of biramous feet, in 
having (10) a simple brain, which, as in some typical Crus- 
tacea (Branchiopoda, &c.), does not supply any of the appen- 
dages, while the structure of (11) the circulatory, (12) inges- 
tive, and (13) reproductive organs agrees with that of the 
Crustacea; and, (14) as we have shown in our embryology of 
Limulus, .... the development of Limulus is like that of 
certain other Crustacea with a condensed metamorphosis, (15) 
the possession of an amnion being paralleled by that of Apus. 
In all essential points Limulus is a Crustacean, with some fun- 
damental features in which it departs from the normal Crusta- 
cean type, and with some superficial characters in which it 
resembles the Scorpion.” 
Of these points numbers 1, 2, and 15 have already been dis- 
cussed in this paper, while numbers 5, 6, and 8 are trivial and 
of no importance. Since Dr. Packard wrote the above, Mr. 
Benham ( J 83) has shown that the thirteenth of these points is 
not true, while the answer to 11 may be found in Professor 
Lankester’s paper. In regard to number 12 I would say that 
in development, except to a slight extent in some Tetradeca- 
pods, Limulus does not agree with the Crustacea, the hypoblast 
being solid and a midgut not appearing until after hatching. 
The origin of the liver and the structure of its ducts are 
greatly different in the two groups. Points 7 and 10 are the 
same and deserve more attention. It has been shown by 
Balfour and by Schimkewitch that in the spiders the ganglia of 
the first pair of appendages are primitively post-oral, and that 
with development they acquire a pre-oral position and eveutu- 
