BUCANIOPSIS. 59 



or entirely closed. Inner lip somewhat thickened. Revolving lines never oblique 

 or wrinkled. 



The type-species is Bucaniopds carinifera, Ulrich, 1 of the Trenton Formation, 

 and the definition of the genus was first given by Ulrich and Scofield in 1897 

 (op. cit., p. 853). 



Perner (op. cit., p. 150) adopts this name and recognises it as a distinct genus, 

 but I am not convinced that the presence of spiral lines is sufficient to warrant its 

 generic separation from Bellerophon, for as Perner points out it agrees in all other 

 respects with Bellerophon, and spiral lines (though subordinate to the transverse 

 ones) are found in the subgenus Sphaerocydus belonging to the latter. However, 

 in the present state of our knowledge it would cause unnecessary confusion to alter 

 the customary usage of the name ; but its relegation to a lower rank as a subgenus 

 instead of a genus appears to be desirable. The name was spelt Bucanopsis by its 

 author, but Bucaiiiopsis is undoubtedly the correct orthography. 



1. Bucaniopsis expansus (Sowerby). Plate X, figs. 1 — 4. 



1839. Bellerophon expansus, Sowerby in Murchison's Silurian System, p. 613, pi. v, fig. 32. 



(?) 1839. Bellerophon gldbatus, Sowerby, ibid., p. 604, pi. iii, fig. 15; p. 613, pi. iv, fig. 50. 



1848. Bellerophon expansus, Ferussac and D'Orbigny, Hist. Nat. Cephal., vol. i, p 185, pl.viii, fig. 1. 



185*2. Bellerophon expansus, Sowerby, McCoy (pars), Syn. Brit. Pal. Fuss. Woodw. Mus.. fasc. ii, 

 p. 309. 



1884. Bellerophon expansus, Sowerby, J. D. La Touclie (pars), Handbook to the Geology of Shrop- 

 shire, p. 81, pi. xix, figs. 643, 644?. 



1909. Bellerophon expansus, Sowerby, Moberg and Gronwall, Orn Fyledalens Grotlanclium (Lunds), 

 Univ. Arsskr., n.f. afd. 2, bd. 5, nr. 1, p. 41, pi. iii, figs. 5, 6, 7. 



Specific Characters.- — Shell involute, composed of a few transverse, rounded, 

 convex whorls ; outer whorl nearly completely enveloping inner ones, some- 

 what straightened and very rapidly expanding in width and height to mouth 

 where it becomes obtusely carinate ; dorsum strongly arched, convex, sides swollen. 

 Umbilicus small, deep, with rounded edges, situated at less than one-third the height 

 of shell. Mouth very large and high, transversely expanded, with wide rounded 

 subcircular lateral lobes, broad reflected lower lip, and open bluntly V-shaped 

 dorsal sinus. Slit-band of moderate width, not raised, but bordered on each side 

 by a narrow thread-like line, and crossed by fine indistinct lunulas and marked with 

 5 — 6 delicate revolving lines similar to but finer than those on rest of shell. 

 Surface of shell ornamented with regular continuous rounded revolving lines, 

 closely placed, of equal or subequal size and rarely interrupted by a few fine 

 simply arched transverse strias curving back to meet slit-band at about 45°. 



Dimensions [28079].- — Height of shell, 15*0 mm.; height of mouth, 1T5 mm.; 

 width of mouth, 16 # 5 mm. 



1 Ulrich and Scofield, op. cit., pp. 853, 922, 925, pi. lxii, figs. 56—61. 



