A REMARKABLE CRUSTACEAN PARASITE, 117 
body itself into which the organs of reproduction 
and digestion are continued, is a feature confined among 
Crustacea to the Ascothoracida and the Ostracoda; a limitation 
the more remarkable, since in almost every group, both of 
Entomostraca and Malacostraca, occur examples of the de- 
velopment of a protective carapace. 
Allowing to these facts the weight which I would assign to 
them, the Cirrhipedia and Ostracoda are brought into more 
intimate relations than has hitherto been admitted. 
Since the phylogenetic significance of the Nauplius larva, 
and more especially the value of its subsidiary features, is still 
under discussion, it is enough to say here that there is no such 
violent discrepancy between the early Nauplius of Balanus 
(the most typical among Cirrhipeds) and that of Laura, the 
only Ascothoracidan with whose development we are acquainted, 
as to necessitate a separation between these two groups. The 
Nauplius of Ostracoda presents a very different appearance 
from the two just mentioned; it is, when freed, already 
enclosed in a bivalve shell, and presents the lateral flattening 
characteristic of the adult; on the other hand, the so-called 
Cypris-stage in the development of Cirrhipedia brings the two 
groups into close proximity. As to its phylogenetic value, 
*it is clear that the Cypris-stage represented more or less . 
closely an ancestral form of the Cirrhipedia, and that both 
the large bivalve shell and the large compound eyes were 
ancestral characters. These characters would seem incom- 
patible with Copepod affinities, but point to the inde- 
pendent derivation of the Cirrhipedia from some early bivalve 
Phyllopod form” (Balfour, ‘Comp. Embryol.,’ i, p. 424). The 
mention made by Balfour of Copepoda refers to the views of 
Claus on the matter, which are most simply expressed by 
reproducing his table of the descent of the Entomostraca! (the 
Protostraca are the “‘ Urphyllopoden” of his earlier writings) : 
1 This phylogeny is indicated in the “‘ Untersuchungen zur Erforschung 
der genealogischen Grundlage des Crustaceen-systems” (Wien, 1876, 4to), 
and the table taken from the ‘‘ Neue Beitrage zur Morphologie der Crusta- 
ceen,” ‘Arb. Zool. Inst. Wien,’ vi, p. 105. 
