ANIMALS. 3 208 
convex margin; occupying the lower half of the margin of each lateral division of 
the dorsal areas. Line of demarcation between the dorsal and the lateral area rather 
slightly defined. Dorsal area bisulcated medio-longitudinally ; the sulcations slightly 
divaricating. Lateral areas narrow. 
Chiton Loftustanus (my discovery of which has elsewhere been noticed!) is a pretty 
species, and appears to have been about two inches in length. The above description 
will probably enable those conversant with the family to decide as to which genus it 
strictly belongs ;” and for this purpose I have taken some pains in endeavouring to 
ascertain the character of the apophyses or processes of insertion of the plates, one of 
which, belonging to an intermediate plate, I have fortunately been able to free from its 
investing matrix. The representations of the intermediate plates in Pl. XVI will afford 
an idea as to their varying form: fig. 11 is suspected to be the second, considering the 
cephalic plate as the first one: fig. 13 may be the third, or one of those behind it: 
fig. 12 is perhaps the seventh or penultimate plate. Fig. 9 represents the cephalic 
plate, which has the apex broken off. Fig. 10 is a representation of the caudal plate, 
which, however, does not give so clear an idea of its form as could be desired; 
owing to the margin of the anterior side (/e/¢ in the plate) bemg too much elevated : 
the consequence is, that this margin appears to be more deeply smuated than it really 
is, and the anterior side is apparently larger than the posterior, which is quite the 
reverse; and, on the other hand, the sinuated character of the vpposite or posterior 
margin is not represented. The posterior portion of the caudal plate is slightly 
concave medio-longitudinally. 
This is an extremely rare species, having only occurred to me in the Shell-limestone 
of Humbleton Hiil. I found two plates of what appear to belong to a Chiton, in 
a fragment of Permian Limestone from Kirkby Woodhouse, Notts, sent to me by 
Mr. KE. W. Binney of Manchester. 
Order CTENOBRANCHIATA, Schweigger. 
PECTINIBRANCHIATA, Cuvier. 
Diagnosis.—< Branchie in the form of sessile, pectinated ridges, contained ina 
cavity.” (Fleming.’) 
Dr. Fleming has divided this group into two sub-orders, namely, //o/ostomata and 
Solenostomata, respectively depending on their shell having the lip of the aperture 
1 Vide Annals and Magazine of Natural History for November, 1844. 
2 Mr. J. W. Salter seems to think, that it is a species of Helminthochiton (vide Quarterly Journal of 
the Geological Society, vol. ili, parti, p. 51); but I cannot agree to this if Helminthochiton Griffithi is to 
be considered as the type of this genus. 
3 British Animals, p. 225. 
