PRESENOE OF EYE8 IN 8HELLS OE OERTAIN CHITONIDAì:. 9 
directly to tlieir source, but it is probable that they proceed 
from thè parietal (brancbial) nerves. When sections cut 
vertically tbrough thè decalcified tegmentum, so as to include 
thè adjacent articulamentum and girdle, thè whole shell and 
its attachments in si tu are examined, I find abundance of 
fibrous structures passing from thè girdle tissues directly to 
join thè plexus of tissue in thè tegmentum. These series of 
fibres are definitely arranged and readily stained, are of deep 
origin, and cannot be regarded as mere processes of thè mantle. 
I bave, however, been unable to trace them to any definite 
source amongst thè muscular tissues. Similar fibres enter thè 
tegmenta on their under sides abundantly along their suturai 
lines. I believe that nerves must accompany these fibres or 
form part of them. Haller describes a series of mantle nerves 
as given oflf from thè branchio-visceral cords between every 
two gills. Each nerve turns outwards towards thè mantle 
border. He was unable to determine whether it also gives 
off fibres which proceed inwards, and supply thè body wall 
beneath thè shells.^ The nerve-fibres are not to be distin- 
guished in thè main stems of thè ramifications from thè tissue 
with which they are bound up, but within thè eye capsules 
thè optic nerves break up into bundles of fine fibres which 
supply thè retina and must be nervous in nature. 
Megalaesthetes and Micrsesthetes. 
From thè ramifications of soft tissue are given off branches 
to each of thè megalopore canals ; these follow thè curved 
course of thè latter and expand within thè megalopores into 
thè papilliform bodies ” of Van Bemmelen, to which I shall 
apply thè name megalsesthetes; believing that they are peculiar 
organs of touch and are at all events peculiar to Chitonidae and 
essentially different in structure and origin to thè spines borne by 
thè girdle in that group. They require a special designation. 
In some species thè strands passing to thè megalopores pass 
' B. Haller, “ Die Organisalion der Cliitoneii der Adria,” ‘ Arbeiten aus 
dem Zool. Inst. der Universitat Wien,’ T. iv, 3 Ileft, 1882, S. 10. 
