30 CRUSTACEA—BRANCHIOPODA CHAP. 
Artemia has rather more, and the blood of Apus is very red. 
The only other Crustacea in which the blood contains haemo- 
globin are the Copepods of the genus Lernanthropus, so that the 
appearance of this substance is as irregular and inexplicable in 
Crustacea as in Chaetopods and Molluscs. 
The nervous system of Branchipus may be described as an 
illustration of the condition prevailing in the group. The brain 
consists of two closely united ganglia, in each of which three 
main regions may be distinguished; a ventral anterior lobe, a 
dorsal anterior lobe, and a posterior lobe. The ventral anterior 
lobes give off nerves to the median eye, to the dorsal organ, and 
to a pair of curious sense-organs, comparable with the larval 
sense-knobs of many higher forms, situated one on each side 
of the median eye; in late larvae Claus describes the 
terminal apparatus of each frontal sense-organ as a single 
large hypodermic cell; W. K. Spencer” has lately described 
several terminal cells, containing peculiar chitinous bodies, in 
the adult. The homologous sense-organs of Limnetis are appar- 
ently olfactory. The dorsal anterior lobes give off the large 
nerves to the lateral eyes, while the posterior lobes supply the 
first antennae. The oesophageal connectives have a coating of 
ganglion-cells, and some of these form the ganglion of the 
second antenna, the nerve to this appendage leaving the con- 
nective just behind the brain. The post-oral nerve-cords are 
widely separate, each of them dilating into a ganglion opposite 
every appendage, the two ganglia being connected by two 
transverse commissures. The ganglia of the three cephalic 
jaws, so often fused in the higher Crustacea, are here perfectly 
distinct. Closely connected with each thoracic ganglion is a re- 
markable unicellular gland, opening to the exterior near the 
middle ventral line; it is conceivable that these cells may be 
properly compared with the larval nephridia of a Chaetopod,’ 
but no evidence in support of such a comparison has yet been 
adduced, 
Behind the genital segments, where there are no limbs, the 
nerve-cords run backwards without dilating into segmental 
ganglia, except in the anterior two abdominal segments where 
‘(The red pigment in Lernanthropus, see p. 68, has been shown to be not 
haemoglobin, so that the presence of this substance in Phyllopod blood becomes 
doubtful.—G.S. ] 2 Zeitschr. wiss. Zool. \xxi., 19092, p. 508. 
3 Cf. Gaskell, Journ. Anat. Physiol. x., 1876, p. 153. 
