112 THE VOYAGE OF II.M.S. CHALLENGER. 



very oblique, and also very little excurved. The ventral outline is very gently arcuate, 

 upcurving at both ends, forming rounded extremities. When the shell is viewed with 

 the posterior end towards the eye the lower edges of the valves are seen to l^e slightl}' 

 tortuous near that part, whence the species has derived its name. The surface of the 

 valves is finely concentrically striated, the sculpture at the hinder part being somewhat 

 finer than in Tdlina semen of Hanley. The ligament is short, yellow, and prominent. 

 The anterior lateral teeth and the plate supporting the ligament are tinged with pale red, 

 the corresponding parts in Tellina semen being white. The pallial sinus is large, deep, 

 rounded at the end, and reaches almost to the front muscular scar. 



In Sowerby's figure 221, a, the anterior dorsal slope and the ventral outline are rather 

 too convex, so that the form appears somewhat too short. 



The types of this species, liljerally presented to the national collection by Mr. G. F. 

 Angas, were dredged in Watson's Bay, South Wales. 



Family D o N a c i D M. 



Donax, Linne. 

 Donax nitidus, Deshayes. 



Donax nitida, Deshayes, Proe. Zool. Soc. Lond., 1854, p. 350. 

 • Donax nitida, Eeove, Conch. Icon., vol. viii. fig. 34. 

 Donax nitidus, Eomer, Concli.-Cab., ed. 2, ji. 51 {no7i. Donax nitidus, Sowerby, Thesaurus, 

 vol. iii. p. 314, pi. cclxxxii. fig. 75). 



Habitat. — Port Jackson, Sydney, in 6 to 15 fathoms, and Station 187, near Cape 

 York, North Australia, in 6 fathoms. 



This species was originally described from specimens said to have been collected at 

 Moreton Bay. It is well characterised by its slender form, its smooth glossy surface, and 

 the conspicuous coarse arcuate sulci and intermediate ridges down the posterior end. 



These do not extend c^uite to the dorsal margin, thus leaving a smooth lanceolate area, 

 which does not, howevei", extend to the posterior extremity of the shell. Although the 

 valves appear smooth and glossy to the naked eye, they nevertheless are ornamented 

 with excessively fine radiating white substrise, such as ol)taiu in many species of the genus. 

 The colour of this species is white, varied with two short livid l)rown rays and a brownish 

 stain upon the sulcated end of the valves. These markings are also faintly visible within 

 the valves, which are otherwise white inside and finely denticulated along the fainth^ 

 ourved ventral margin. M. Deshayes described this species as totally white, -with the 

 exception of a pale violet flesh-coloured lunule. This is not, however, correct, either as 

 regards the types in the Cumingian collection or the Challenger specimens, all of which 

 exhibit the rays above mentioned. 



