278 Cephalopoda in Tate and Blake's * Yorkshire Lias.' 
Again the Blake collection contains a specimen [B.M. No. C. 18065], 
75-7 mm. in diameter, labelled in his handwriting : ‘A. mutatus. M. 
Lias. Peak. ’ Blak6 places Simpson’s A . mutatus with a ? in the synonymy 
of Simpson’s aculeatus, and in his observations on the latter species 
writes : ‘ The A. ynutatus of Simpson I have not seen, but I think, by 
its description, it must belong here.’ It would seem therefore that this 
specimen came into Blake’s possession after the publication, or at any 
rate the writing, of his remarks on Simpson’s species aculeatum, and this 
may account for Peak not being mentioned in the 1 Geological position. ' 
of the species as given by Blake. 
AEgoceras validum Simpson sp. (p. 278). 
No example of this species has been recognised in the Blake collection, 
AEgoceras sociale Simpson sp. (p. 278). 
No example of this species has been recognised in the Blake collection. 
AEgoceras tubellum Simpson sp. (p. 278). 
No example of this species has been recognised in the Blake collection. 
AEgoceras taylori J. de C. Sowerby sp. (p. 279). 
Respecting this species, Blake states : ‘ The two varieties of this 
rare shell which Quenstedt indicates by the names nodosus and costatus 
are very dissimilar, and their scarcity in Yorkshire would have prevented 
their being united ; but as they occur together, and the most tuberculated 
form is seen itself to vary in the number of tubercles, as noticed by Simpson 
and marked by his two names [ cornutus and quadricornutus] , we are not 
in a position to overrule the dictum of foreign geologists, that they 
must be considered one species. We may, however, designate the less 
tuberculated form as var. lamellosum, the presence of which does not 
seem to have been noticed, or it would certainly have received a name.’ 
A specimen in the Blake collection [B.M. No. C. 17981], about 53 mm. 
in diameter (excl. the spines), is labelled in Blake’s handwriting: 
‘ A. Taylori, base of M.L. R. Hood’s B.’ It is strongly tuberculated, 
there being twelve tubercles in each row in the outer whorl. The same 
collection includes a more definitely costate and less tuberculate form 
[B.M. No. C. 17982], labelled in Blake’s handwriting : ‘ Am. cornutus, 
base MX. R.H.B.’ [i.e., base of the Middle Lias, Robin Hood’s Bay]. 
This may be the less tuberculate form which Blake proposed to designate 
as var. lamellosum, ‘ the presence of which,’ he states, ' does not seem 
to have been noticed, or it would certainly have received a name.’ 
The ‘ Geological position ’ of the species is given as : ‘ Sub-zone of 
A. armatus , Robin Hood’s Bay.’ 
AEgoceras jamesoni J. de C. Sowerby sp. (p. 279). 
The Blake collection does not contain any Yorkshire examples of 
this species. 
AEgoceras br evispinum J. de C. Sowerby sp. (p. 280). 
Yorkshire examples of this species have not been recognised in the 
Blake collection. 
AEgoceras regnardi d’Orbigny sp. (p. 280). 
Yorkshire examples of this species have not been recognised in the 
Blake collection. 
AEgoceras heberti Opjiel sp. (p. 280). 
This species is not represented in the Blake collection. Blake states : 
' The only example I have seen is in the York Museum, and agrees 
perfectly with d’Orbigny’s figure.’ As to the ‘ Geological position,’. 
Blake states : ‘ Unknown, but probably sub-zone of A. armatus.’ 
Naturalist 
