122 SUPPLEMENT TO GREAT OOLITE MOLLUSCA. 
tab. 172, of which numerous specimens are now in the British Museum, obtained from a similar geological 
position in Somersetshire ; in some of these the last volution quite conceals all the others, leaving only a 
small umbilical orifice; the absence of coste upon the inner portion of the last volution distinguishes it 
from 4. macrocephalus. Dr. Oppel (‘Juraformation,’ p. 478) proposes for it the new title of 4. Morrisi, 
which, in accordance with the above views, must remain as a synonym of JA. viator. 
Acteonina? parvula, Part I, p. 104, alter the generic title to Ceritella. 
Part II, Tab. 5, figs. 18 @,19 a. Both these figures represent the young condition of Trigonia 
Goldfussii. : 
Trochus pileolus, Part I, p. 66, Tab. 10, fig. 5. Additional specimens have proved that the smooth- 
ness of the surface is accidental; traces of encircling striations are sometimes visible; the shell then 
becomes identical with Zuréo obtusus, Sow., of which Trochus Bixa, D’Orb., is also a synonym. 
Nerita hemispherica, Roem., Tab XI, figs. 14, 16; Nerita minuta, Sow., Tab. XI, fig. 19. A com- 
parison of very ample materials, including all the connecting forms, leaves no choice but to regard N. 
hemispherica as the adult shell of N. minuta. The preservation of the epidermal pattern of coloration has 
materially tended to this result; the older shells, as in fig. 14, with their strong, rugose plications, thickened 
columellar lip, and entire absence of the epidermal coat, appear at first sight sufficiently distinct, but from 
these we pass to specimens of less advanced growth, as in fig. 16, without plications, but still possessing 
the callosity upon the inner lip; some in this state, however, retain portions of the external tegument, in 
which may be traced remains of the two broad bands of white between the three of dark-coloured pigment, 
the latter consisting of transverse, wrinkled lines. From these to the smallest forms the transition is easy ; 
the latter are most commonly more ovate, but this is by no means an invariable feature, nor are the adult 
shells very constant in the degree in which the spire is produced. The minute forms, which usually retain 
the epidermal coat, are smooth and shining; with advance of growth the shell exhibits continual and 
considerable increase of thickness. The two extremes of aspect are fairly represented in figs. 14 and 19. 
Nerita minuta is so inappropriate a name for the adult shell, that it seems desirable to adopt Nerita 
hemispherica, although the former has priority. 
Fusus ? subnodulosus, Part I, Tab. V, fig. 9, p. 23, alter the generic title to Brachytrema. 
Phasianella conica, Part I, Tab. XI, fig. 30, p. 74; Phasianella acutiuscula, Tab. XI, fig. 28, and 
Tab. IX, fig. 2. An examination of numerous additional specimens has led to the conclusion that these 
forms should be regarded as only varieties of one species, for although some examples are even more 
lengthened than the figures of P. acutiuscula, others connect the typical specimens of each variety in a 
very perfect manner. 
Genus Brachytrema, Part I, p. 24. Further information has shown that the generic description before 
given should be slightly modified ; the outer lip was stated to be thin, which is correct as far as regards the 
greater number of specimens ; but some species, as B. varicosa and B. pygmea, acquired at certain arrests 
of growth thickened outer lips or varices, as in Triton; from the latter genus they are distinguished by the 
shorter trochiform spire and absence of denticulations upon the borders of the aperture. 
Turbo? pygmeus, Tab. IX, Part I, figs. 29, 29 a, alter the title to Brachytrema pygmea. The doubt 
as to the genus expressed in Part I, p. 65, has been justified in an example with the aperture perfect, figured 
by M. Piette, ‘Bull. de la Soc. Géol. de France,’ 2 ser., pl. xv, fig. 21, under the name of Brachytrema 
brevis ; the base is strongly striated, and the aperture much contracted. 
Alaria levigata, p. 17, Tab. Ill, figs. 3, 3a; Tab. XLI, fig. 13, alter the title to Alaria Myurus, 
Desl., sp. It was stated at p. 17 ‘that in everything excepting its smooth surface this shell agrees with the 
Rostellaria Myurus of Deslongchamps.”’ A specimen recently obtained exhibits some encircling striations 
upon the upper portions of the two larger volutions; the sole distinction, therefore, that separated it from 
