160 CLASS III. GASTEROPODA. ORDER VII. PECTINIBRANCHIATA. 
to them has become of infinite value, for we now have species in which 
this peculiarity operates in different forms ; some, for example, are found 
with merely a few small pebbles agglutinated to the earlier whorls, whilst 
others have nothing but flat, tile-shaped pieces collected only round the 
periphery of the whorls. We doubt not but that other modifications of 
this character will yet be discovered, and we trust that the Phori will ere 
long be made the subject of a strict anatomical examination ; the genus 
is undoubtedly one of interest, and cannot fail to be esteemed by con- 
chologists. , 
The shell of Phorus may be described as being orbicular, nearly conical, 
and obtuse at the spire ; the whorls are of regular formation, are more or 
less agglutinated over with fragments of stones or shells, and have the 
periphery sometimes ornamented with long hollow spines ; the under face 
of the shell is rather concave, granular or lamellated, and there is a large 
deep umbilicus, which is, however, often concealed by age ; the aperture 
is depressed, with the margins disjoined, and the lip simple and acute. 
The operculum is thin, horny and oval. 
Examples. 
Pl. CCXIV. Fig. 1 and 2. 
Puorus soxaris, Nobis, Proceedings Zool. Soc., 1842. 
Trochus solaris, Linneeus. Chemnitz, Conch., vol. v. t. 173. f. 1700 and 
1701. Lamarck, Anim. sans vert., vol. vii. p. 10. 
Pl. CCXIV. Fig. 3, and Pl. CCXV. Fig. 8. 
Puorus onustus, Nobis, Proceedings Zool. Soc., 1842. 
Trochus agglutinans, Lamarck, Anim. sans vert., vol. vii. p. 14. 
Trochus conchyliophorus, Born. 
Pl. CCXIV. Fig. 4. 
Puorus paLiiputus, Nobis, Proceedings Zool. Soc., 1842. 
Pl. CCXIV. Fig. 5. 
Puorus corrueatus, Nobis, Proceedings Zool. Soc., 1842. 
