ORTHOCERAS. 129 



0. capillosum, Barrande,^ 0. recticmctum, Blake,^ and 0. Grindrodi, Blake,^ have 

 them very much closer and finer. 



The indistinct longitudinal ornamentation, sometimes to be seen, approximates 

 it to 0. araneosum^ Barrande,* but that species differs in the size of the siphuncle, 

 the narrowness of its chambers, its generally curved form, and in other respects. 



0. nohile, Barrande,'is very similar in many respects, but its siphuncle is generally 

 more excentric ; its septa are much more distant ; and its minor markings are more 

 regular. It has close ribs in the apical part (not seen in any of our specimens) ; and 

 there are no signs of any longitudinal marks, which, though indistinct, exist in the 

 English specimens ; and for these causes I cannot unite them. 0. Duponti, Barr.,® 

 and 0. severum, Barr./ besides presenting similar divergences, with the exception of 

 having no rings, have the additional difference of the siphuncle being still more 

 excentric. The chambers of the last species are deeper than in the English fossil. 



O.palus, Barrande,® seems to have finer closer markings and a smaller siphuncle ; 

 the septa are not shown. 0. asparagus, Barrande,^ as seen from a specimen in 

 the British Museum, is exactly similar in ornament, but its septa are very much 

 more distant, being more than half the diameter of the shell apart. 



5. Oethoceeas Vicarii, Whidborne. PI. XIII, figs. 3—7, 9, 9 a, 9 b. 



cf. 1888. Oethoceeas Dannenbeegi, Foord. Cat. Foss. Ceph. Brit. Mus., p. 84. 

 1889. — ViCAEii, Whidborne. Geol. Mag., dec. 3, vol. vi, p. 29. 



Description. — Shell very elongate, straight, very slightly conical. Section 

 circular. Shell-structure thin. Siphuncle small and slightly excentric. Chambers 

 very concave, moderately deep, their height being to their width in the ratio of 



1 1868, Barrande, * Syst. Sil. Boheme,' vol. ii, pt. 3, p. 486, pi. cccxxv, figs. 19—33 ; pi. ccclvii, figs. 

 4—7 ; and pi. cccxciv, figs. 16—19, Efc. E— H. 



2 1882, Blake, ' Mon. Brit. Foss. Ceph.,' pt. 1, p. 121, pi. xi, fig. 4. 



3 Ibid., p. 122, pi. ix, fig. 9. 



* 1868, Barrande, ' Syst. Sil. Boheme,' vol. ii, pt. 3, p. 283, pi. cccxxxvii, figs. 1 — 9 ; pi. cccxxxviii, 

 figs. 1 — 14 ; pi. cccxxxix, figs. 1 — 14 ; and pi. cccxl, figs. 1—17, Et. E. 



^ 1866, Barrande, ' Syst. Sil. Boheme,' vol. ii, pt. 3, p. 336; pi. ccxxviii, figs. 2—4; pi. cclxxxiv, 

 figa. 1 — 19 ; pi. cccxi, figs. 1 — 7 ; pi. cccxii, figs. 1 — 7 ; and pi. cccxiii, figs. 1 — 10, Et. E. 



6 Ibid., p. 324, pi. cclxxxv, figs. 1—17 ; and pi. cccxxiv, figs. 7-10, Et. E. 



^ Ibid., p. 384, pi. ccci, figs. 1 — 5 ; also pis. cexix, ccxxi, &c., Et. E. 



8 1870, Ibid., p. 535, pi. ccclxiv, figs. 12—14, Et. F. 



9 1868, Ibid., p. 428, pi. cccxvii, figs. 1—5, Et. E. 



