PELECYPOUA. 987 



Genus 1. CHIONE, Megerle, 1811. 



Ghione, Megerle von Miihlfeld, Mag. Ges. Naturf. Freuntle, Berlin, v, 1811, 

 51. Type : Venus cancellata (L.), Lamarck. Chiona, M<">rch, 1853. 



Animal having the mantle-margins plicate-dentate ; siphons short, 

 broad, unequal, united at the base, the branchial with 2 rows of cirri, 

 the anal ciliated. 



Shell ovately triangular, more or less thickened or subcordiform ; 

 margins of the valves finely crenulated. Hinge narrow, solid, with 

 3 cardinals in each valve. Pallia! sinus small, triangular. Lunule 

 circumscribed by an incised line ; escutcheon not limited by any line, 

 and defined chiefly by a deficiency of coarse sculpture, and a more or 

 less pronounced ridge from the beaks towards the posterior margins. 

 Ligament inset, visible externally. Sculpture variable, concentric 

 ribs or lamellse and less-prominent radials. 



Distribution. Seas of most tropical and temperate countries. 



Subgen. 1. CHIONE, s. str. 



Type : C. cancellata, L. Circomphalus, Adams, 1857. Oinphaloclathrum, 

 Tryon, 1884 ; not Morch, 1853. Not Chione, Gray, 1838. 



Sculpture of radial ribs decussated by concentric, sharp, elevated 

 lamellae ; 3 cardinals in each valve, the teeth are usually entire and 

 smooth or feebly channelled. 



Sect. 1. TIMOOLEA. Brown, 1827. 



Timoclea, Brown, 111. Conch. Gt. Brit., expl. pi. 19, f. 11. Type: Venus 

 ovata. Pennant. Pasiphae, Leach, 1852 ; not Risso, 182(i. Leukoma, 

 Romer, 1857. Leucoma, Stoliczka, 1871 ; not of Stephens, 1829. 

 Cytherea, H. and A. Adams, 1857 ; not of Bolten, 1798. Murcia (part). 

 Romer, 1857 ; not Koch, 1835. 



Sculpture predominantly radial, the concentric element feeble : 

 the middle left and 2 posterior right cardinals grooved ; the escutcheon 

 smooth. Siphons united to their orifices. 



1. Chione Stutchburyi, Gray, 1828. Plate 61, figs. 4, a. 



Venus Stutchburyi, Gray, in Wood's Ind. Test., Suppl., 1828, f. 4 ; Yate 

 N.Z., 308 ; Dieff. N.Z., 250 ; Thes. Conch., ii, 1853, f. 50, 51 ; Conch. 

 Icon., xiv, 1863, f. 59. Chione Stutchburyi, Gray, C.M.M., 70 ; Grit. 

 List, 45 ; Ereb. & Ter., 0, pi. 3, f. 4 ; Mutton, J.' de Conch., xxvi, 49 ; 

 M.N.Z.M., 148 ; P.L.S. N.S.W., ix, 522 ; Index, 89 ; Suter, T.N.Z.I., 

 xxxix, 269. Venus zelandica, Quoy and Gaimard, Voy. Astrol., iii, 1835, 

 522, pi. 84, f. 5, 6. Cardita zelandica, Potiez and Michaud, Gall, des Moll., 

 1838, 166. Venus Dieff enbachi, Gray, Dieff. N.Z., 250 (young shell) ; 

 C.M.M., 70. Chione Madeayana, T. -Woods, P.R.S. Tas., 1879, 38. 



Shell ovato-cordiform, subtrigonal. swollen, thick, radiately ribbed 

 and concentrically ridged, fulvous. Beaks prominent, inflated, in- 

 curved and directed forwards, situate at about the anterior fourth 

 of length. Anterior end short, rather narrowly convex, the dorsal 

 margin straight and rapidly descending ; posterior end convex, the 



