PACKARD.] ANATOMY OF NEBALIA. 437 
still more rudimentary, one-jointed, and with but few sete, which are 
stiff and coarse. These resemble the simple, unbranched Sth and last 
pair of abdominal feet in Copepoda (Calanus ¢). 
The long, slender terminal segment bears two very long, narrow cer- 
copods (Pl. XXXVI, fig. 7) ending in one large and several small setz, 
but there is no telson; the cercopods are simple, the integument entirely 
smooth, with no striz or any other markings, and they are edged exter- 
nally with short and internally with long ciliated sete. In the absence 
of a telson Nebalia differs from Cuma or any other Decapod, and in this 
respect, and the simple cercopods, shows a close resemblance to the termi- 
nal segment with its two setiferons cercopods of the Copepoda. Accord- 
ing to Claus the males differ from the female in WV. geoffroyi in the rather 
narrower carapace and slighter body, but chiefly in the very long 2d 
antenne, the flagellum of which reaches nearly to the end of the caudal 
appendages. The male sexual glands open on the last of the eight 
thoracic segments, which fact Claus regards as a proof of the agreement 
of Nebalia with the Malacostracous type. 
Internal anatomy.—Claus remarks in his “Untersuchungen zur Erfor- 
schung der genealogischen Grundlage des Crustaceen-Systems” (1876) 
that in all the internal systems of organs Nebalia is considerably re- 
moved from the Phyllopoda, and shows an immediate relationship to the 
Malacostraca, sometimes approaching near the Amphipoda, sometimes _ 
near the Myside. The nervous system consists of a large two-lobed 
brain and of a ventral cord extending through all the limb-bearing seg- 
ments, there being, as shown in Metschnikoff’s Fig. 25 of the embryo, 
17 ganglia, corresponding to the 17 limb-bearing segments of the body 
behind the head. <A transverse section of a ventral ganglion of N. bipes 
(Pl. XXXVI, fig. 9, or Fig. 66, in text, ng) shows a form of ganglion 
quite unlike that of the Hstherta and other Phyllopods (Pl. XXIV, fig. 
9, ng; XXXII, fig. 8, G, Gt; XX XIT, fig. 2, ng; XIV, fig. 4, ng; XX XI, 
fig. 5, gang.), in which the ganglia are separate, connected by rather long 
transverse commissures, whereas in Nebalia the pair of ganglion are con- 
solidated and of the form of the Decapod ganglion, as also pointed out 
by Claus, who says that there is a very close resemblance in the form of 
the nervous centers to the ventral ganglionic chain of the Myside. 
We have endeavored to obtain good sections of the brain of Nebalia 
bipes, and Fig. 65 (in the text) will serve to illustrate tolerably well the 
form and intimate structure of the supra-cesophageal ganglion. The 
brain is very small, and the section represented was the third from the 
front of the head. The ovaries (ov) pass into the head, the end of each 
ovary overlying the brain. The brain itself is composed of two lobes 
closely united, and seen in section the brain is as deep as broad, with a 
constriction passing around the outside in the middle. The histological 
structure is very simple, with nothing approaching the complex nature 
of the Decapodous brain. Each division or ganglion of the brain is 
composed of nucleated ganglion-cells, the nuclei large and distinct, as 
seen in Fig. 66 a, and imbedded in a fine granular substance ( puntzswod- 
stance). At the lower part of each ganglion the fibers forming the com- 
missures are quite distinct. Whether the 1st antenne or both pairs are 
innervated from the brain Claus does not state, and we have been un- 
able to observe. It is probable, however, that at last the 1st antennal 
nerves arise from the brain, judging from Metschnikoft’s Fig. 25, wherein 
he shows a nerve descending from the under side of the ganglion, while 
the cesophageal commissures are directed backward; and we feel uncer- 
tain whether the descending nerves in our figure are the 1st antennal 
