280 Cephalopoda in Tate and Blake's ‘ Yorkshire Lias.’ 
inches in diameter and labelled in Blake’s handwriting : “ Am. capri- 
comus, Whitby,’ that may be the specimen mentioned by Blake as 
‘ certainly the adult of AEg. capricovnum . ’ 
The Blake collection also contains three specimens each named 
Am. arcigerens . . One of these [B.M. No. C. 18061], 25-2 mm. in diameter, 
and labelled in Blake’s handwriting : ‘ Am. arcigerens Peak,’ exhibits 
the angular deflection [of the ribs] on the front, referred to by Blake, 
and would probably therefore have been included by Blake in AEgoceras 
defossum Simpson. Another specimen [B.M. No. C. 18062 1 , 24 mm. in 
diameter, and labelled in Blake’s handwriting: 'Am. arcigerens, R. 
Hood’s B.’ ; and a third [B.M. No. C. 19227], 18-5 mm. in diameter, 
and labelled in Blake’s handwriting : ‘ Am. arcigerens, M. Lias. Peak,’ 
were probably referred by Blake to AEgoceras capricornum, Schlotheim 
sp. The collection contains also three other specimens, 22 mm., 19 mm., 
and 12 mm. in diameter respectively not labelled, of which, one, the 
medium-sized specimen exhibits the forward angular deflection of the 
ribs, observable in Simpson’s species defossus and omissus, species which 
are referred by Mr. Buckman to the genus Oistoceras . 
AEgoceras defossum Simpson sp. (p. 282). 
An unlabelled specimen in the Blake collection [B.M. No. C. 17988] 
is clearly the original of Blake’s PI. VIII., fig. 9, the imperfection of the 
anterior part of the fossil being well represented in the figure, which 
depicts the fossil of about the natural size. It was in a small tray with 
three other specimens,* one [B.M. No. C. 18062], labelled ‘ Am. arcigerens, 
R. Hood’s B.’ ; another [B.M. No. C. 18061] labelled ‘Am. arcigerens 
Peak ’ ; whilst the third [B.M. No. C. 18063] is without any information. 
Since the ' Geological position ’ of the species given by Blake is : ‘ Zone of 
A. capricornus, Staithes, Hautcliff [probably a typographical error for 
‘ Huntcliff],’ Robin Hood’s Bay,’ the locality of the figured example is 
uncertain. It is, however, to be observed that its matrix agrees fairly well 
with that of the example from Peak [B.M. No. C. 18061].- Buckman 
(Yorkshire Type Ammonites, part III., 1911, 27) refers Blake’s figured 
example to Simpson’s Ammonites omissus and places it in the genus 
Oistoceras. Blake’s collection contains another example of the same 
species [B.M. No. C. 19251], 33 mm. in diameter, but this is unlabelled 
AEgoceras diver sum Simpson sp. (p. 282). 
It would seem from Blake’s remarks that he only saw two examples 
of this species; one he figured (PI. VIII., fig. 3). His description seems 
to be based upon Simpson’s type -specimen. We have not recognised 
an example of the species in the Blake collection. 
AEgoceras sinuatum Simpson sp. (p. 283). 
Blake merely quotes Simpson’s description of this species and adds : 
‘ A specimen in the Whitby Museum agrees well with the description, 
and I cannot identify it with any other form.’ By stating (in brackets) 
at the end of the description ‘ 1 ex.,’ it would appear that Blake saw 
only this one example, at any rate, the species does not appear to be 
represented in his collection. 
Arietites bucklandi J. Sowerby sp. (p. 283). 
The Blake collection neither includes the figured specimen (PI. V., 
fig. 2), nor any example of the species either named by Blake, or that 
can be referred to this species as defined by Blake. He writes of this 
species as a ‘ characteristic, though rare, shell in Yorkshire,’ and states 
that it ‘ is [in Yorkshire] only found, to our knowledge, at Redcar, where 
* See ante under AEgoceras capricornum. 
Naturalist 
