ORTHOCERAS. 145 



they are high. Septa slightly oblique and arching. Surface apparently smooth, or 

 possibly very finely reticulate. 



Size. — One of Mr. Vicary's specimens is 7-| inches high, by 1^ inches in 

 greatest diameter. A specimen in my Collection is 1^ inches wide, although 

 its body-chamber is absent. A small specimen has a diameter of only 2 mm. at 

 its broken apical end. 



Locality. — This is the commonest Orthoceras at Wolborough. There are 

 fourteen specimens in Mr. Vicary's Collection, eleven in the Museum of Practical 

 Geology, one in the Battersby Collection of the Torquay Museum, four or five in 

 the British Museum, and one in my Collection. 



Remarks. — Almost without exception the surfaces of these specimens have 

 been roughened and partially destroyed by fossilization, and there is no indication 

 that they bore any ornament, except that in one of Mr. Vicary's specimens a fine 

 reticulation is just discernible under the lens. It is doubtful whether this may 

 not have been caused by weathering, but on the whole it looks too regular to be due 

 to such an accidental cause, and therefore it is probable that the external shell was 

 minutely reticulate. The shells are characterised by their peculiar contour, 

 slightl/ unsymmetrical rather than actually curved, and expanding (as mentioned 

 by Phillips) in the upper regions. It would appear that in the young state its 

 shape was rather more slowly tapering than in the aged shell. 



I had for some time a doubt whether the specimen which Phillips figured as 

 205 a is really the same as the rest of his specimens of this species, and this doubt 

 seems to be shared by Mr. Foord, but an examination of Mr. Vicary's large series 

 of specimens appears to set the question at rest. 



Though Phillips evidently is dealing in his ' Palgeozoic Fossils ' with the 

 species to which these Newton specimens belong, his description presents some 

 divergences from them. The chambers are said to be one-third or one-fourth their 

 diameter in height, instead of one-sixth, the siphuncle is said to be excentric, and the 

 section elliptic in the ratio of 10 : 12. It is possible that the state of preservation 

 of the specimens, or their age, or the confusion with Sowerby's 0. undalatum, may 

 account for these slight discrepancies. On the other hand, the fusiform shape near 

 the mouth, mentioned by Phillips, is well marked in our specimens, and they agree 

 perfectly with his figures 205 a, h, c, d, both in shape and in the height of their 

 chambers. I have not had the opportunity of comparing the Newton fossils with 

 any South- Petherwin specimens. Possibly the figures 205 a and b refer to them ; 

 but 205 c and d are evidently taken from Wolborough fossils. 



The nomenclature of the species presents much difiiculty. Sowerby^ described 

 a Carboniferous species, calling it 0. undulatum, in 1814. In 1822 Schlotheim* 



1 1814, Sowerby, ' Min. Conch.,' vol. i, p. 130, pi. lix. 



2 1822, Schlotheiu), ' Petref.,' vol. i, p. 55, pi. xi, fig. 1. 



