26 
Proceedings of the Royal Society 
Monday, 5th January 1885. 
EDWARD SANG, Esq., LL.D., Vice-President, in the Chair. 
The following Communications were read : — 
1. Anatomy and Physiology of Patella vulgata. Part I. — 
Anatomy. By R. J. Harvey Gibson, M.A. Com- 
municated by Professor Herdman, D.Sc. 
(Abstract.) 
This paper forms the first half of Part I. of a research into the 
minute anatomy, physiology, and development of Patella vidgata. 
The paper aims at giving a complete account of this form in both its 
physiological and morphological aspects. It treats, first of all, with 
the external features and rough anatomy. The epidermal system is 
then treated in detail. Some interesting modifications of the super- 
ficial epithelium are described. The epithelial cells are usually 
elongated columnar, with processes connecting them with a dense 
subepithelial layer of connective tissue. The attachment of the 
circular muscle is covered with modified epithelium, the epiblast 
cells not being absent in that region, as is said to occur in the case 
of the adductor muscles of Anodon. The modified epithelium at 
one spot near the base of the tentacle functions as an eye. The 
cells are there pigmented, and the cuticle is modified so as to form 
a double layer, with intervening trabeculae. The retinal epithelium 
springs from a nerve plexus, which is supported by a mesh-work of 
connective tissue fibres, with large lacunae. 
The arrangement of fasciculi in this muscular system points un- 
mistakably to the attachment of Patella to a rock, being the result 
of muscular contraction and formation of a vacuum beneath the 
foot. 
The muscle fibres are non-striped, save in the heart. 
The gills are morphologically processes of the ventral surface of 
the mantle, which is itself physiologically an accessory respiratory 
organ. The epithelium is in the mantle and gills columnar, and 
the cells are not close to each other, thus permitting of gaseous 
exchange between them. 
