636 PROFESSOK E, RAY LANKESTER, 
Limuli neither with the Arachnida nor with the Crustacea, 
but in a group apart. The fact that this investigator did 
not attempt a complete study of the skeleton of Limulus, 
and a comparison of that and other organs with the corres- 
ponding parts of the Arachnida, Kurypterina, and Crustacea, 
sufficiently explains the conclusion at which he arrived. 
He confessedly made use of but few data, and those such as 
he himself brought to light in the case of Limulus. The 
value of his contributions to our knowledge of the ana- 
tomical structure of the King Crab are not in any way 
diminished by the vulnerability of the conclusion which he 
based upon them. 
With regard to the conclusions of Dr. A. 8. Packard, it 
is difficult to avoid an expression of surprise. We owe to 
Dr. Packard the important observation of the late appear- 
ance of the chilaria, and other observations as to the seg- 
mentation of the telsonic region in the young Limulus, and 
the primitive connection of the genital operculum with the so- 
called abdomen rather than with the cephalothorax. He has 
probably seen more of young and old King Crabs than any 
other naturalist, and yet, writing in 1880 (No. 9), with all 
the literature before him, with all the facts under his hands, 
he still maintains that the Limuli are Crustacea, examines 
the aphoristic statements of Van Beneden to the effect that 
they are Arachnida and rejects them. Dr. Packard simply 
adopts from Dohrn the group of Gigantostraca as Claus has 
done, and as Gegenbaur has done; but whilst Gegenbaur 
uses for it the old term Peecilopoda, Packard thinks it 
necessary to bestow upon it the new name Paleocarida. 
An examination of Dr. Packard’s latest memoir on 
Limulus will, I think, show that he clings to the notion 
that Limulus is a Crustacean, and is unable to perceive that 
its true place is among Arachnida, because he entertains 
certain erroneous preconceptions as to the value of the 
various parts of an arthropod body as indicative of genetic 
affinity. A respiratory appendage, however, unlike in 
structure to anything seen in Crustacea, is, if it acts as a 
branchia, to be considered as “ of the Crustacean type ” 
according to Dr. Packard. This is a simple confusion of 
logical categories. It is true that many Crustacea have 
branchial appendages, but it does not follow as a conse- 
quence that all branchial appendages are borne by Crusta- 
ceans, or that such appendages are of “the Crustacean 
type.” So too Dr. Packard speaks of “ true antenne ” and 
a ‘true mandible,” “a thorax,’ and “an abdomen,” ag 
though these were recognised and definable elements o¢ 
