REPORT ON THE CUMACEA. 53 



The uropoda (see PI. VIII. fig. 15) are very slender and about as long as the five 

 posterior caudal segments taken together. The scape is remarkably elongate, and pro- 

 vided at the inner edge with a great number of ciliated denticles, somewhat unequal in 

 size. The branches exhibit a structure similar to that in the female, but the number 

 of denticles occurring along the inner edge of the inner branch is far greater, being no 

 less than twenty-seven, besides the terminal spine. 



Nervous System. — In dissecting two specimens of this species, a male and a female, 

 I succeeded in isolating the greater part of the ventral ganglionic cord, and have 

 figured the most anterior part of this cord of the female specimen (PI. VII. fig. 13), and 

 the succeeding part from the male specimen (PI. VIII. fig. 5). The central part of the 

 nervous system in all Cumacea consists, besides the supraoesophageal ganglion or brain 

 (visible in PL VIII. fig. 1), of sixteen ganglia, ten of which belong to the anterior 

 division, and the six others to the tail. Of the former the three anterior (PL VII. 

 fig. 13), innervating the oral parts, are closely crowded together and almost confluent, 

 whereas the remaining seven ganglia (see PL VIII. fig. 5), belonging to the trunk, are 

 widely separated and connected by rather long double commissures. The three 

 posterior of these ganglia are, however, somewhat closer together than the four pre- 

 ceding, and the last ganglion is also a little smaller. Between each pair of the com- 

 missures connecting the six anterior ganglia of the trunk there is also a narrow median 

 cord, which at first sight has the appearance of another central commissure con- 

 necting the ganglia. On closer examination, however, this part is found to consist of 

 a continuous vessel running along the dorsal surface of that part of the nervous cord, 

 to which it is partly connected, and apparently representing the ventral artery. The 

 caudal ganglia {ihid,) are far less developed and only slightly dilated, whereas the 

 commissures are very long and slender. All the ganglia consist of two well-marked 

 symmetrical halves and give origin on each side to two or three strong nerve-trunks, 

 which soon ramify and enter the corresponding limbs. Another rather large nerve- 

 trunk is seen to issue from the commissures themselves, and seems to innervate the 

 musculature of the corresponding segment. The mandibles together with their com- 

 plex muscles are innervated by two strong nerves issuing fi'om the oral commissures at 

 their junction with the ventral cord (see PL VII. fig. 13), each nerve dividing succes- 

 sively into a great number of diverging branches (partly visible in PL VIII. fig. 1). 



Development. — As above stated, the female specimen dissected had the marsupial 

 pouch filled with embryos. These were all in the same rather early stage of develop- 

 ment (PL VII. figs. 14-17), merely forming rounded saccular bodies, lined by a 

 thin pellucid cuticle (the egg-membrane). On a closer examination several of the 

 limbs were found in their first stage of development, as rounded buds along the 

 strongly curved ventral surface. On the opposite side a slight sinus occurs, indi- 

 cating the dorsal curvature characteristic of the Cumaceau embryos (fig. 14). The 



