HARPOCERAS ELEGANS. 447 



with several leaf-like cells on the sides. The inner saddle is constricted in the middle, 

 and surrounded by numerous folioles on the sides. There are three thick auxiliary 

 lobes, and three narrow saddles between them, where they disappear under the spiral 

 suture. The suture line is seen in situ on PI. LXIII, fig. 4, and an enlarged drawing 

 of it is carefully drawn in PI. LXIII, fig. 7. 



Affinities and Differences. — Harp, ovatum is distinguished from the other congeneric 

 species by its ovoid whorls without vertical or concave folds at the inner margin, by having 

 a prominent keel with two lateral sulci, and by being provided with only faint sigmoidal 

 radii, every two springing from a common stem. This species more closely resembles 

 Harp, radians than any of the other forms with which it is associated in the Upper 

 Lias of Yorkshire. 



Locality and Strati graphical Position. — This species appears abundant in the jet- 

 rock and hard shales of the Upper Lias near Whitby and Runswick ; it is rather an 

 abundant fossil, but most of the examples are very rough and deformed ; it is rare, there- 

 fore, to find so good an example as the one which I have figured as a type of the species. 



Harpoceras elegans, Young and Bird, PI. LXIII, figs. 1 — 3. 



Ammonites elegans, Young and Bird (non Sowerby). Yorksb. Coast, p. 267, pi. xiii, 



fig. 11, 1828. 



— candidus, aVOrbigny. Terr. Jurass. (no description), pi. 63, 1842. 



— elegans, Simpson. Monogr. of the Lias Ammon., p. 31, 1843. 



— — — Fossils of the Yorksh. Lias, p. 72, 1855. 



Diagnosis. — Shell discoidal, compressed, subcarinated ; whorls slightly convex, two- 

 thirds involute ; spiral angle acute, with a concave slope on the penultimate whorl ; 

 inner third concave, outer two thirds slightly convex ; siphonal area narrow, sloping, 

 with an elevated ridge in the middle ; radii simple, sigmoidal, well marked in young 

 shells, and becoming very delicate with age ; aperture elongated and sagittate, with two 

 slightly prominent lateral lappets. 



Dimensions. — Transverse diameter 100 millimetres; height of the last whorl 38 

 millimetres ; width of umbilicus 24 millimetres ; height of aperture 27 millimetres ; 

 width 20 millimetres. 



Description. — This is another common Whitby Ammonite which has hitherto been 

 badly drawn, as shown in pi. xiii, fig. 11, of Young and Bird's work. Some authors 

 refer this Ammonite to Ammonites elegans, Sow., but none of the specimens I have 

 examined correspond with Sowerby's figure, which does not appear to be a Lias shell at all ; 

 as I have not seen the type specimen I refrain from further criticism. The figure which 

 approaches nearest to this fossil is that given by d'Orbigny in his pi. lxiii, under the name 



