ANIMALS. ‘Yor 
plate by figures 20, 21, 22, 23, 24, 25, 29, 30): possibly they are specifically 
distinct :' and it is this idea which causes me to be particular in stating, that the 
Tunstall Hill form must be considered as the type of the species. ‘The variety 
Humbletonensis appears to graduate the latter into the Strophalosia Cancrini, which, 
however, in addition to the other distinguishing characters already noticed, has its 
large valve too much vaulted to be confounded with the form in question. 
Strophalosia Morrisiana, considered in all its modifications, may be readily 
distinguished from the two species last described. It is decidedly more regular in 
form than S. Goldfussi; and the area, although wider, is not so high (vide Pl. XII, 
fig. 19): the spines too, are not so numerous. It agrees with S. excavata in form and 
in the size of the area ;? but in this species the spines are far more numerous and more 
regular in their arrangement; though in the latter respect there is a simulation on the 
part of S. Morrisiana. The present one differs from both species in having the valves 
striated, and the spines adpressed. 
There is a singular peculiarity in this species requiring to be mentioned. I have 
seen several specimens of the rounded variety, found at Humbleton Quarry, appearing 
as if trivalved; but whether it is due to accidental circumstances I am not prepared to 
say: its occurrence in several specimens seems to negative this conclusion. I have 
had represented in Plate XII, figs. 20, 21, 22, 23, 24, two of my specimens displaying 
this character; leaving it to be cleared up by future researches. Full grown 
specimens of the same variety occasionally show the anterior margins arching and 
gaping so as to approximate to the form of the circular or elliptical orifice of Productus 
proboscideus before its tube becomes developed. I still think that this singular 
modification has been caused by the flowing in and out of the currents which supplied 
the mollusc with the necessary quantity of nutriment and fresh air.’ 
In making the Orthothrix lamellosus of Geinitz synonymous with this species, 
notwithstanding the former is stated to be without spines on the small valve, I have 
been influenced by certain of my specimens displaying lamellee on this valve somewhat 
similar to those represented in the ‘ Verstemerungen, at figures 15a, 16, 17a, 21, 
in Plate V. The fossils identified by Dr. Geinitz (vide Pl. VI, figs. 16, 17, 18) with the 
Strophalosia Cancrini, | readily recognise as belonging to 8. Morrisiana. 
1 T designate the Humbleton form Strophalosia Morrisiana, var. Humbletonensis : in case it should be 
found to be a distinct species, the varietal may be conveniently used for the specific name. 
The area is represented too high by nearly one half in the restored medio-longitudinal section repre- 
sented in Plate XI, fig. 21; further, the spies are too much elevated, and the large valve is rather too 
convex for the typical form. 
8 « Koninek, from an examination of Productus proboscideus, supposes that it (the genus generally) 
was attached by means of fibres passing out of the anterior opening, which would compel us to conclude 
that the genus did not belong to the Palliobranchiata. Instead of the anterior tubular opening of 
P. proboscideus subserving such an office, I cannot but think that it simply served as a passage for the 
ingress and egress currents.” (Vide Annals and Mag. of Nat. Hist., vol. xxiii, p. 93.) 
