Cephalopoda in Tate and Blake’s ‘ Yorkshire Lias / 283 
but with the ribs joining towards the outside by cross bars.’ He gives 
as its v. Geological position ’ : ' Zone of A . Bucklandi , Marske.’ The Blake 
collection now includes no specimen which has been or can be identified 
with this species. 
Arietites stellaris J. Sowerby sp. (p. 287). 
Blake states than in Yorkshire ‘ good examples of this species are not 
common,' and that ‘ they range from ^ an inch to a foot in diameter.’ 
The Blake collection includes a specimen [B.M. No. C. 19990], 36 mm. 
(or rather more than if inches) in diameter, labelled in Blake’s hand- 
writing : ‘A. stellaris, 56 R. Hood’s B.’ As the ‘Geological position ’ 
of the species Blake gives : ‘ Zone of A', oxynotus (base), Robin Hood’s 
Bay, Marske (boulders).’ 
Arietites obtusus J. Sowerby ( sp . (p. 287). 
Respecting this species Blake merely states-: ‘ This may be taken 
as the final step of Arietites towards AEgoceras in one direction, the 
similarity between it and /Eg. sagittarium being great.’ As the ‘Geol- 
ogical posiHon ’ he gives : ‘ Zone of A. oxynotus. Common at Robin 
Hood’s Bay at the base of the series, and not growing to a large size.’ 
The Blake collection includes two examples each labelled in Blake’s 
handwriting: ‘A. obtusus, R. Hood’s B.’ The larger example [B.M. 
No. C. 1 9991] is about 62 mm. in diameter ; it has flattened whorls, 
and is carinate up to its anterior extremity, possessing a distinct furrow 
on each side of the keel. The smaller specimen [B.M. No. C. 19992] 
is 35 - 5 mm. in diameter ; its whorls are inflated, and on the anterior 
part of the last whorl the keel is quite obsolete, so that the specimen 
greatly resembles Blake’s AEg. sagittarium. 
‘ Ammonites cervicornis .’ 
The Blake collection includes an ammonite [B.M. No. C. 19232], 
44' 5 mm. in diameter labelled in Blake’s own handwriting : ‘ Am. 
cervicornis M. L. Peak,’ but this species does not appear to be mentioned 
in his work either as a valid species or as a synonym. The species seems 
to be allied to Sowerby’s A. bvevispina. It is a very evolute shell, its 
other dimensions at its greatest diameter (44-5 mm.) being : height of 
outer whorl (incl. ribs), 12 mm. ; width of umbilicus, 24 mm. ; thick- 
ness of outer whorl (incl. ribs), about 10 mm. 
Arietites scipionianus d’Orbigny sp. (p. 287). 
A specimen in the Blake collection [B.M. No. C. 17909] is certainly 
the original of his figure 3 on Plate V., which represents the fossil of 
about the natural size. It is marked in Blake’s handwriting : ‘ PI. A., 
fig. 3,’ and bears no locality label. The specimen is entirely septate. 
Respecting the ‘ Geological position ’ of the species in Yorkshire, Blake 
writes : ‘ Zone of A. Bucklandi (upper part), Marske, Redcar. Not 
found in situ at Robin Hood’s Bay, but in blocks associated with Lima 
pectinoides , Lucina limbata, Dentalium etalense, Cerithium etalense, thus 
indicating the horizon.’ As the specimen bears no locality label, its 
locality is somewhat doubtful ; but as ‘ Marske ’ is the first -mentioned 
locality, there is great reason for regarding that as the locality of the 
figured example, there being two other examples attributed to this 
species from the other locality (Robin Hood’s Bay) in the Blake collection 
[B.M. Nos-. C. 17931 and C. 17932]. 
Arietites semicostatus Young and Bird sp. (p. 288). 
The example [B.M. No C. 17935] of this species figured by Blake 
(PI. VI., fig. 4 a (upper figure) is on the same block with AEgoceras Pauli 
Dumortier already mentioned (see supra p. 274). 
Arietites difjormis Emmrich (p. 289). 
A specimen in the Blake collection [B.M. No. C. 17933], evidently 
1922 Aug.-Sept. 
