SANGUINOLITES STRIATO-GRANULATUS. 393 



have never seen any approach to granulation, or the possession of radiating rows 

 of tubercles on their surface. 



Sanguinolites STRIATO-GRANULATUS, sp. nov. Plate XLII, figs, 16 — 22. 



Sanguinolites tricostatus, cle KonincJc, 1885. Apu. Miis. Roy. Hist. Nat. 



Belg., torn, xi, p. 81, pi. xv, figs. 14, 15. 



Specific Characters. — Shell oblong, below medium size, diagonally gibbose, 

 very inequilateral, somewhat narrowed posteriorly in the dorso- ventral diameter. 

 The anterior end is very short, compressed, its upper margin excavated by a large 

 lunule, its border rounded. The inferior border is almost straight, produced, 

 meeting the posterior border at an obtuse angle. The posterior border is 

 obliquely truncate from above downwards and backwards, nearly straight, 

 meeting the hinge-line at a well-marked obtuse angle. The hinge-line is arched 

 iu front, straight behind, nearly as long as the valve. The umbones are small, 

 narrow, incurved, and contiguous, not much elevated, and placed in the anterior 

 sixth of the valve. A well-marked angular ridge passes obliquely downwards and 

 backwards from the umbones to the postero-inferior angle, separating a compara- 

 tively large and compressed, bat convex dorsal slope from the rest of the valve. 

 Another low but erect ridge passes from the umbo to the postero-superior angle, 

 separating the dorsal slope from the large, elongate, but shallow escutcheon. 

 The dorsal slope is crossed by two radiating lines. The valve, anterior to the 

 ridge, is somewhat compressed by a broad, oblique, shallow, nearly obsolete sinus. 



Interior. — The anterior adductor muscle-scar is very large, pyriform, and 

 occupies the greater part of the anterior portion of the valve. It is bounded 

 behind by a well-marked ridge, which descends nearly to the lower border. The 

 posterior adductor scar is shallow, and placed in the upper margin, remote from 

 the posterior end. Pallia! line entire. Hinge normal. The inner surface of the 

 valve is almost smooth with concentric shallow grooves and laminee, crossed by 

 obsolete radiating striee. The dorsal slope has one or two radiating grooves. 



Exterior. — The surface is ornamented with fine but irregular concentric lines 

 of growth, with an occasional deep sulcus in some individuals, pointing to a 

 temporary cessation of growth from some cause or other. The posterior two- 

 thirds of the valve is covered by radiating lines of small tubercles, present also on 

 the dorsal slope. The dorsal slope is crossed by one or more radiating lines or 

 obsolete ridges. Shell moderately thick. 



51 



