PERIPHERAL NERVOUS SYSTEM IN NBMERTINES. 433 
(pi. viii, fig. 3) no lateral branches are indicated in the 
drawing, 
Keferstein writes (‘ Zeitschr. f. Wissensch. Zoologie,^ 
Bd. xii, p. 80) ; Aus den Seitennerven treten in regel- 
massigen Abstanden (pi. v, fig. 10) feine Nerven, mit 
breiter Basis entspringend, aus, die ich nur bis auf unbe- 
deutenden Abstand vom Seitennerven verfolgen konnte und 
die wahrscheinlich hauptsachlich in die Hautspgehen.” 
The figure in which he indicates these peripheral nerves 
implanted upon the longitudinal trunks is again, in this 
case, one of the Hoplonemerteans, viz. Amphiporus 
splendidus. 
Macintosh is the first to make separate mention of the 
state of things as he finds them in the armed and unarmed 
species. 
Of the first he says A Monograph of British Annelids, 
A. Nemerteans^ p. 83) : The branches given off by these 
trunks are generally pale and indistinct, but by the use of 
dilute acetic acid in Amphiporus lactifloreus, and in others 
without such aid, they can be satisfactorily observed. They 
are easily seen, for instance, in Amphiporus pulcher, the 
reddish colour which tinges them at their commencement 
shining through the translucent integuments. An elaborate 
plexus of branches from the lateral trunks has also been 
noticed in these species” (pi. xvi, fig. 3), 
Of the unarmed species he writes as follows (ibid.,p. 110) : 
“ Branches probably exist, but only faint traces of such 
are seen in the longitudinal sections, for the opacity of the 
textures in the living animal prevents their being satisfac- 
torily made out.” 
Macintoshes very hesitating affirmation 'concerning the 
presence of peripheral branches in the unarmed Nemerteans 
is certainly a step in advance of his predecessors, who did not 
notice any difference in this respect, who principally ex- 
amined and only figured armed species, and regarded the 
facts as they found them in this subdivision at the same 
time as normal and typical for the whole order. In this way 
the error has for a long time persisted, which I now hope to 
clear away definitely, that the peripheral nervous system of 
the Nemerteans corresponds in general to the type of the 
Hoplonemertini, in which it was first described and 
figured. 
My own investigations of the Hoplonemertini did not 
furnish any new results worthy of note. I found the small 
branches given off by the longitudinal trunks as the above- 
cited naturalists have described them. These branches 
