106 HYATT, 



able to the base of the epistonie, but are then lost to view in 

 the thickness of the endocyst (Figs 10, 11, T'). 



The remaining pair, the Lophophoric Nerve-trunks, 

 are placed somewhat more to the dorsal side, but have con- 

 fluent bases with the corresponding Epistomic Nerve- 

 trunks. They divide into four branches, two on each side, 

 one pair going obliquely and dorsally to the lophophore 

 and the others in an anterior direction to the evaginable 

 endocyst on the dorsal side (Figs. 9, 10, 11, T'"). The 

 lophophoric branches separate squarely when they reach 

 the lophophore into four smaller branches (Figs. 9, 10, 11, 

 U). Two of these, the Oral Branches, pass abdominally, 

 each one halfway round the oral aperture throwing off fila- 

 ments to the bases of the tentacles, and finally terminate 

 in two tentacular filaments, which are lost at the junctions 

 of the base of the central tentacle with the adjoining sides 

 of the approximate tentacles (PL 15, fig. 1, XT'). The re- 

 maining pair, the Brachial Branches, are much shorter, in 

 consequence of the i-ound outline of the lophophore. The}^ 

 traverse the lophophore in a dorsal direction giving ofi" fil- 

 aments to the few tentacles on that side, and terminate, 

 also, in two tentacular filaments, at the junction of the 

 median pair of tentacles behind the epistonie. 



Tiie nervous filaments disappear at the junction of the 

 bases of the tentacles, and cannot be traced into them, but 

 each one probably splits into two branches which climb 

 the approximate sides of every pair of tentacles, one branch 

 on either side. On the dorsal side, however, where the 

 basal junction of the central pair of tentacles comes direct- 

 ly upon the median line, this mode of distribution is viola- 

 ted. There are two filaments, respectively the ultimate 

 nervules of the right and left brachial branches, which 

 come together, and must be distributed at this single, me- 

 dian junction. They, however, do not appear to enter 

 the cavity of the tentacles, but cross them to the opposite 

 sides from which they came and distribute themselves to 

 the approximate sides of the pair. 



The anterior branch, or Polypidal Nerve-branch, strikes 

 off abruptly from tlie main trunk (Figs. 9, 10, 11, T'"), 



