Vol. 52.] OF THE CHALK ROCK. 77 



better marked. The suture-line of B. baculoides has not been 

 observed in English specimens ; but the figure given by d'Orbigny 

 from a French example differs from B. bohemicus in the greater 

 length of the lobes and saddles, and in having the siphonal saddle 

 and the superior-lateral saddle of about the same size. 



Remarks. — Geinitz considers that B. bohemicus is identical with 

 B. baculoides of Mantell, which is found in the Lower Chalk of 

 Sussex, etc., and he regards the forms figured under the same name 

 by d'Orbigny from the French Cenomanian as distinct, proposing to 

 place them in his species sub-baculoides ; he takes as his types speci- 

 mens found on the same horizon in Saxony. The specimen from 

 the Priesen Beds of Bohemia figured by Fritsch (1893) is of great 

 interest, as it shows the earliest part of the shell with the initial 

 chamber. The examples of B. bohemicus found in the Chalk Bock 

 are far from perfect, and the mode of preservation often leaves much 

 to be desired; the longest portion that I have seen measured 

 87 mm., with a thickness of 9 mm. and a height of 12 mm. 



Localities. — England : Chalk Bock of Winchester, Lichfield 

 (Hants), Cuckhamsley, Boxmoor, and Luton. France: zone of 

 Terebratulina gracilis east of the Paris basin, zone of Epiaster brevis 

 at Fontaine-les-Yervins. North-western Germany : zone of Hetero- 

 ceras Beussianum at Oerlinghausen, Langelsheim, Heiningen, etc., 

 and rarely in the zones of Inoceramus Brongniarti and I. Cuvieri, 

 Saocony : Planer-Kalk (zone of I. Brongniarti) of Strehlen and 

 "Weinbohla. Bohemia: Turonian and Priesen Beds of Priesen, 

 "Waldeck, Bohmisch-Kamnitz, and Leneschitz. 



Family Prionotropidse, Zittel. 



Genus Peionocycltjs, Meek, 1 1872. 



Pkionoctcltjs Nepttjni (Geinitz), 1849. (PI. II. fig. 11, and PI. III. 

 figs. 1-4.) 



1842. Ammonites falcatus, H. B. Geinitz {non Mantell), ' Char, der Schichten u, 

 Petrefacten der sachs.-bohm. Kreidegeb.' (Heft 3), p. 67. 



1850. Ammonites Neptuni, H. B. Geinitz, ' Das Quadersandst. oder Kreidegebirge 

 in Deutschland,' p. 114, pi. iii. f. 3; 1872. C. Schliiter, ' Cepb. oberen deutsch. 

 Kreide,' p. 36, pi. xi. f. 1-7 ; 1872. A. Fritsch and U. Schlonbach, ' Ceph. bohm, 

 Kreideformat.' p. 30, pi. iii. f. 4, pi. xiv. f. 3 ; 1874-5. H. B. Geinitz, ' Das Elbtbal- 

 gebirge' (Palaeontographica, vol. xx.), pt. 1, p. 280, pi. lxii. f. 4; pt. 2, p. 185, 

 pi. xxxvi. f. 4 ; 1877. A. Fritsch, ' Stud, im Gebiete der bobm. Kreideformat. II. Die 

 Weissenberger und Malnitzer Scbicbten,' p. 101 ; 1887. A. Peron, ' Notes pour servir 

 a l'Hist. du Terr, de Craie,' Bull. Soc. Sci. bist. et nat. de l'Yonne, ser. 3, vol. xiL 

 p. 136. 



1855. ? Ammonites Br uvaisianus, D. Sbarpe, 'Foss. Mollusca in tbe Chalk of 

 England ' (Ceph.), p. 52, pi. xxiii. f. 8, 9. 



Description. — Shell discoidal, carinate, with a wide umbilicus. 

 Whorls rather more than one-third enclosing, subquadrangular in 

 section, ornamented with very strong and slightly oblique ribs, each 

 of which bears near the siphonal margin two tubercles, the inner 



1 F. B. Meek, in Hayden's Ann. Rep. U.S. Geol. Survey of the Territories- 

 (1872), p. 298 (footnote), and ibid. vol. ix. (1876) p. 452. 



