FACKAHD.] ANATOMY OF NEBALIA. 437 



still more rudimentary, one-jointed, and -with but few setse, which are 

 stiff and coarse. These resemble the simple, unbranched 5th and last 

 pair of abdominal feet in Copepoda {Calanus 9 )• 



The long, slender terminal segment bears two very long, narrow cer- 

 copods (PI. XXXVI, fig. 7) ending in one large and several small setoe, 

 but there is no telson; the cercopods are simple, the integument entirely 

 smooth, with no striae or any other markings, and they are edged exter- 

 nally with short and internally with long ciliated setse. 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 setiferous cercopods of the Copepoda. Accord- 

 ing to Glaus the males differ from the female in N. geoffroyi in the rather 

 narrower carapace and slighter body, but chiefly in the very long lid 

 antennae, 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 Glaus regards as a proof of the agreement 

 of uSTebalia with the Malacostracous type. 



Internal anatomy. — Glaus remarks in his "Untersuchungenzur Erfor- 

 schung der genealogischen Grundlage des Grustaceen-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 Mysidce. 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. hipes 

 (PI. XXXVI, fig. 9, or Fig. 66, in text, oig) shows a form of ganglion 

 quite unlike that of the JEstheria and other PhvUopods (PI. XXIV, fig. 

 9, ng; XXXI, fig. 8, G\ G'; XXXII, fig. 2, ng ; XIV, fig. 4, ng; XXXIII, 

 fig. 5, gang.), in which the ganglia are separate, connected by rather long 

 transverse commissures, whereas in Xebalia the pair of ganglion are con- 

 solidated and of the form of the Decapod ganglion, as also pointed out 

 by Glaus, who says that there is a very close resemblance in the form of 

 the nervous centers to the ventral ganglionic chain of the Ilysidce. 



We have endeavored to obtain good sections of the brain of Nehalia 

 hipes, and Fig. 65 (in the text) will serve to illustrate tolerably well the 

 form and intimate structure of the supra-oesophageal 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 Decai)odous brain. Each division or ganglion of the brain is 

 composed of nucleated ganglion-cells, the nuclei large and distinct, as 

 seen in Fig. 6Q a, and imbedded in a fine granular substance {puntzsub- 

 stance). At the lower part of each ganglion the fibers forming the com- 

 missures are quite distinct. Whether the 1st antenna?: or both pairs are 

 innervated from the brain Glaus does not state, and we have been un- 

 able to observe. It is probable, however, that at last the 1st antenual 

 nerves arise from the brain, judging from Metschnikoff's Fig. 25, wherein 

 he shows a nerve descending from the under side of the ganglion, while 

 the oesophageal commissures are directed backward ; and we feel uncer- 

 tain whether the descending nerves in our figure are the 1st antennal 



