70 
NAUTILOIDEA. 
1857. Orthoceratites angulatum, Boll, Archiv fiir Mecklenburg, xi. 
Jabrg. p. 24, Taf. vii. f. 21. 
1866. Orthoceras migulatum, Barrancle, Syst. Sil. de la Boheme, vol. ii. 
Texte iii. 1874 (janyier), p. 692, pi. ccxxxiii. If. 1-3. 
1866. Orthoceras Bacchus, Barrande, ibid. p. 237, pi. ccxiii. fl. 10-13, 
pi. cclxx., pi. cclxxi. ff. 1-21. 
1868. Orthoceras ponder osiim, Barrande, ibid. p. 213, pi. ccLxvi. ft*. 1, 2, 
pi. cclxxi. ff. 22, 23. 
? 1873. Orthoceras angidatum, Salter, Cat. Cambr. & Sil. Foss. p. 158. 
? 1882. Orthoceras Bacchus, Blake, British Foss. Ceph. pt. i. p. Ill, 
pi. ix. ff. 3-7. 
[_Not 1867. Orthoceras angidatum, Hall, 18th Beg. Bep. p. 353i, 
pi. xix. (x.) ff*. 10, 11, — 1875. Orthoceras angidatum, "Worthen & 
Meek, in Worthen’s Geol. Sury. of Illinois, yol. vi. pt. 2, Palaeont. 
p. 504, pi. xxiv. ff. 8, 8«. — 1882. Orthoceras angidatum, Blake, 
loc. cit. p. 106, pi. yii.] 
Sp. Char. Shell slightly curyed. Section circular, or yery 
slightly elliptical. Bate of increase 1 in 5. Length of the body- 
chamber 24 times its basal diameter. Septa about L the diameter 
of the shell. Siphuncle yariable in position, generally about mid- 
way between the centre and the margin, but sometimes still nearer 
the centre. Surface ornamented with prominent, acute, longi- 
tudinal ribs (from 26 to 30 in a circumference) which conform to 
the conical growth of the shell, slowly increasing in their distance 
from each other as the latter expands. Between these there are from 
one to three prominent acute riblets or thread-like lines, running 
parallel to the ribs. The latter are always present in casts, but the 
riblets are too fine to leaye any traces beneath the test. Feeble 
transyerse annulations may be seen in well-preseryed examples of 
the young shell, crossing the longitudinal ornaments at right angles. 
Bemarks. Finding the nomenclature of this species in a yery 
unsatisfactory state, owing to the different interpretations put upon 
Wahlenberg’s description, I communicated with Dr. Lindstrom, of 
Stockholm, with a yiew to ascertain whether any of Wahlenberg’s 
original types of 0. angidatum still existed in the Palaeontological 
Museum of Dpsala. He informs me in reply that he has lately 
inspected an old collection of fossils in the Uniyersity of Upsala 
called the “ Marklin Collection,” a gift to the Fniyersity on the 
part of Marklin, a contemporary of Wahlenberg. In this collection 
Dr. Lindstrom found specimens named 0. angulatum, such as the 
Swedish palaeontologists haye been accustomed to recognize under 
that name, stating that, An his opinion, Hisinger's, as well as 
Marklin’s interpretation of 0. angidatum, expresses what Mahlen- 
berg, the author of the species, implied in his description of it. 
