ORTHOCERAS. 139 



? 1882. Obthoceeas suBANiiruLAEE, Blahe. Mon. Brit. Foss. Ceph., pt. 1, p. 94' 



pi. V, figs. 6, 6 a. 



? 1888. — — Foord.^ Cat. Foss. Ceph. Brit. Mus., vol. i, 



pp. 59 and 94. 



Description. — Shell elongate, slightly conical, tapering in the ratio of about 

 1:16. Section circular. Septa very concave, slightly oblique and arching ; very 

 distant, their height being about one-third or two-Mths of their width. Siphuncle 

 central, large. Surface bearing three broad, low, indistinct, rounded rings or 

 bulges on each segment (which appear rather sharper and more distinct on the 

 inner shell) ; and covered both on the rings and hollows with sharp, distant, 

 prominent, transverse lines, with sloping sides, and somewhat unequal in height, 

 which have the appearance of being slightly imbricated by longitudinal markings, 

 and are about eight times as numerous as the rings. 



Size. — The larger specimen in the Museum of Practical Geology, measuring 

 114 mm. in length, is 18 mm. wide at the upper extremity. 



Locality. — There is a small portion of the septal part, consisting of almost three 

 chambers, in my Collection, which I believe to have come from Wolborough ; and 

 two othe^ specimens, one of which is very long, in the Museum of Practical 

 Geology from the same locality. 



BemarJcs. — There is, in the opinion of both Mr. Roberts and myself, no reason 

 for hesitating about the identification of these fossils with Miinster's species, as 

 they agree in every respect both with his figure and description. Supposing that 

 there is no mixing of species under this name, it appears to be common to both 

 the Silurian and the Devonian of England and the Continent. The ribs in 

 Miinster's species are more rounded than in our specimens, but they are described 

 by him as being sometimes sharp : our fossils agree with his in the central position 

 of the siphuncle and in the circular section; but, on the other hand, M'Coy 

 asserts that neither of these points are correct if judged by the fossils of Miinster's 

 locality ; and Barrande's figures of the species bear him out in this respect. In 

 fact, there is much reason to doubt the identity of Barrande's 0. suhannulare^ with 

 the present fossil ; as it has more distant chambers and unimbricated and oblique 

 ribs and riblets, which do not seem to be so sharp as those in our form. 



Eoord^ gives a full description of 0. subannulare as occurring in the Wenlock 

 Shale and the Bohemian Etage E, which, while generally agreeing, differs from our 

 specimens in the important particular that the depth of the chambers is stated to 

 be two-thirds instead of two-fifths of their width. 0. discretum, Barrande,* has, 



^ For other synonyms of the Silurian species see Foord, loc. cit. 



2 1866, Barrande, ' Syst. Sil. Boheme,' vol. ii, pt. 3, p. 343, pi. cclxxxiii, figs. 1—19, &c., Et. D 

 (colony) and E. 



3 1888, Foord, ' Cat. Foss. Ceph. Brit. Mus.,' vol. i, p. 53. 



4 1868, Barrande, ' Syst. Sil. Boheme,' vol. ii, pt. 3, p. 276, pi. cclxxix, figs. 38—48, Et. F. 



