30 CRETACEOUS GASTROPODA 
Formations. Trichinopoly and Arrialoor groups, only the three last named 
localities refer to the latter; the species is far more frequent in the first named 
group. 
Til. ALARIA, Morris & Lycett, 1854. 
1. AZLARIA ParKinsoni, Mantell, Pl. II, Figs. 5—8. 
1864. Aporrhais Parkinsoni, Mantell. Pictet Mat. p. 1., Pal. Suisse, 3me. ser. Foss. Ste. Croix, 2d. pt. p. 604. 
with synonyms and references to other authors. 
Al. testa elongata, turrita; anfractibus numerosis convexis, primis 3—4A levi- 
gatis, ceteris transversaliter costulatis, spiraliter striatis : costulis circiter 18 im wno 
circuitu, parum curvatis atque obliquis, utringue attenuatis, nonnullis rectis, varices 
quoddam fortiores representantibus, in ultimo anfractu paucioribus atque prope margin- 
em exteriorem gradatim evanescentibus ; striis numerosissunis, nonnullis prope sutu- 
ram posteriorem fortioribus atque distantioribus ; ultimo anfractu subinflato, gibboso ; 
rostro moderate-longo, acuto ; labio calloso, partem inferiorem ultimi anfractus tegente 
labro alato; ala lata, brevi, postice intus ad anfractum antepenultimum decurrente, 
ad marginem exteriorem acute uncinata atque in utroque latere unci trsinuata, antice 
ad peripheriam angulata atque rursus late msinuata. 
Spiral angle 28°—32°, sutural angle 8°—9°. 
Pictet gave in his ‘ Paléontologie Suisse,’ such a thorough critical examination 
of this species, that it is scarcely necessary to add any thing to the knowledge of its 
literature. A comparison of our figures with those already existing will shew, that 
the form of the shell and of the whorls, together with their ornamentation and the 
wing, are in every way so exactly identical with the European species, that no 
remarkable difference can be traced out. 
The first three or four, probably embryonal, whorls are quite smooth, with a 
polished surface (Fig. 7). They seem to become filled out by growth with a solid 
mass of shell-substance, inasmuch as they disappear altogether on the cast of the 
shell (vide Fig. 5). The perfect shell seems to have been covered with a thin coat 
of callose mass, obliterating somewhat the finer ornamentation on the surface. The 
last whorl including the anterior canal is about one-fourth longer than the spire 
(vide Fig. 5). As regards the wing, our specimens, so far as they are complete in 
this point, resemble much more the English figure in “Geol. Trans. IV., Pl. XVIIL., 
Fig. 24,” than that of Pictet in his ‘Gres verts;’ the differences arise probably much 
more from the imperfectness of the specimens, than from being actual variations, 
although both may be accounted for, especially as in all the species of the dzara 
the form of the wing so much differs with their age. It would no doubt be very inter- 
esting to know whether such a variation does exist, and whether it is to that amount 
admissible within the limits of the species. If it be, then a very close comparison 
appears necessary of the specimens known as 2. Parkinsoni with R. Reussi, Geinitz. 
The figures given by Reuss and that of Woodward (Geologist 1861? Pl. XI. Fig. 1) 
show the only difference in the anterior margin of the wing. I need scarcely repeat, 
that the wing in Péerocera, Rostellaria and others attains its perfectness only very 
