Newell. — On the Anatomy of the Limpet. 159 



The oiiontophore is armed with four tooth-Hke processes 

 arranged in a series. Those of the inner series are of a brown 

 horny colour at the apex, and transparent round the base. 



The odontophore is about four times the length of the body of 

 the animal, it is shown in position, [d, e, fig. 2,) after removing 

 the foot. The teeth in the body of the coil are much sharper 

 than those near the mouth, showing that they are replaced from 

 behind as fast as they are worn out by friction in triturating 

 the food. The muscular system round the odontophore is shown 

 in fig. 2. 



The branchicc are numerous lamellar processes like ampullae, 

 lying between the fringe of the mantle and the foot ; they do not 

 extend all the way round the edge of the mantle, but only up to 

 the sides of the neck ; in Patella vuhjata, figured by Cuvier, they 

 extend round the whole body. 



Nervous System. — As the nervous system seems to be the 

 distinguishing feature between Patinella radians and Patella 

 vulyata, I have dissected it out with great care. In P. vulgata 

 the nervous system is simply a ganglionic ring, giving out nerve- 

 fibres to the wdiole body. But in P. radians there are three 

 different pairs of ganglia : (1 .) Pedal ganglia are two ganglionic 

 masses on the surface of the foot, connected together by a short 

 thick commissure {ab, fig. 5) ; they are connected to the parieto- 

 splanchnic ganglia by two very short commissures {ca, and hd, 

 fig. 6), and to the cerebral ganglia by two long commissures 

 (ae, and bf, fig. 5). These pedal ganglia give off two nerve-fibres 

 to the surface of the foot {ah, and bh', fig. 5), nearly meeting at 

 their posterior ends. (2.) The parieto- splanchnic are not so large 

 as the pedal ganglia ; they are situated outside of and above the 

 pedal, and connected to them by short commissures, to one 

 another by a long commissure passing round the neck (cd, 

 fig. 5), and to the cerebral ganglia by two commissures {df, and 

 ce, fig. 5). These ganglia give off nerves {m, m', fig. 5,) to the 

 mantle, and nerves [k, k', fig. 5,) to the sides of the somatic 

 cavity, and the nerve g, fig. 5, to the visceral cavity. (3.) The 

 cerebral ganglia are situated in the top of the head at e,f, fig. 5 ; 

 they give off" nerves to the tentacles, and one going round the 

 top of the head {ei-f, fig. 5). 



Eeproductive Organs. — There is a large ovary shown in fig. 2 

 {hn), but I have not been able to trace the openings to the 

 surface. I noticed that this ovary is much larger in summer 

 time. 



Muscular System. — The chief muscular organ is the foot ; it 

 covers the whole of the lower surface of the body, and acts like 

 a sucker, attaching the animal to a rock. The circular muscle 

 attaches the mantle to the upper rim of the foot. Its position 

 is shown in fig. 2 (pg). From this muscle the mantle hangs 

 free round the foot. The muscles surrounding the head, and 



