332 REPORT—1885. 
In 1880 Professor Claus, ‘ Lehrbuch der Zoologie,’ writes, ‘This re- 
markable form (Nebalia) was for a long time regarded as a Phyllopod, 
and in many of its characters it represents a connecting link between the 
Puytbopopa and the Maracosrraca. The structure and segmentation of 
the head and thorax resembles that of the Malacostraca, but the terminal 
region of the abdomen does not present the special form of a caudal plate 
or telson. In Nebalia we probably have to do with an offshoot of the 
Phyllopod-like ancestors of the Matacosrraca, which has persisted to the 
present time.’ He adds, ‘ Nebalia is best placed in a special group 
Lerrostraca, between the Enromostraca and Mauacostraca. The Paleo- 
zoic genera Hymenocaris, Peltocaris, &c. would have to be placed in such 
a group.’ } 
‘It is,’ writes Professor Claus, ‘in the highest degree probable that 
all these’ (Palseozoic PHytLocaripa) ‘are not true Phyllopods, but have 
belonged to a type of Crustacea, of which now there are no living 
representatives, but which, taking their origin from forms allied to the 
lower types of Entomostraca, have prepared the way for the Malaco- 
stracan type. Such a connecting link, which has served to the present 
day, we evidently find in the genas Nebalia.’ ? 
In his ‘ Handbuch der Paliontologie,’ Munich, 1885, Professor Dr. K. 
A. Zittel adopts Packard’s order Puyniocartpa, but places it under the 
Matacostraca, and between the EprRIi0PHTHALMIA and the Mrrostomata. 
In his article on the Paleozoic allies of Nebalia, Dr. A. S. Packard, jun., 
thus sums up the Payiiocaripa: ‘ From our total lack of any knowledge 
of the nature of the limbs of the fossil PuyLtocarrpa, we have to be guided 
solely by analogy, often an uncertain and delusive guide. But in the 
absence of any evidence to the contrary, there is every reason to suppose 
that the appendages of the head, thorax, and abdomen were on the type 
of Nebalia, since there is such a close correspondence in the form of the 
carapace, rostrum, and abdomen. But whatever may be the differences 
between the fossil forms represented by Ceratiocaris, &c., they certainly 
seem to approach Nebalia much nearer than any other known type of 
Crustacea; they do not belong to the Dscaropa; they present a vague 
and general resemblance to the zoéa or larva of the Decapods, but no zoéa 
has a telson, though one is developed in a postzoéal stage; they do not 
belong to any other Malacostracous type, nor do they belong to any exist- 
ing Entomostracous type, using those terms in the old sense. No 
naturalist or paleontologist has referred them with certainty to the 
Decapods or to any other Crustacean type than the Phyllopods. To this 
type (in the opinion of Metschnikoff and Claus, who have studied them 
most closely) they certainly do not belong, and thus reasoning by ex- 
lusion they either belong to the group of which Nebalia is a type, or they 
are members of a lost, extinct group. The natural conclusion, in the light 
of our present knowledge, is that they are members of the group repre- 
sented by the existing Nebalia.’ ‘The differential characters separating 
them from the Decapods or any other Malacostracous type are— 
1. The loosely-attached carapace, the two halves connected by an 
adductor muscle. 
Claus, translated by Sedgwick (Cambridge), p. 448 (footnote), 8vo, 1884. The 
Leptostraca (Claus) are thus defined: ‘ Crustacea with thin, folded carapaces, mostly 
bivalved, under which all the thoracic rings remain as free segments’ (Zittel, 
“ Handb. Paliontol.’ 1885, p. 655). 
? Claus in Siebold and Kolliker’s ‘ Zeitschrift,’ xxii. 1872, p. 329. 
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