64 MAZATLAN BIVALVES 



Tablet 267 contains 2 minute valves, the smallest "03, across, 

 which, may belong to this species. 



Tablet 268 contains 2 young specimens. — ^269, 2 sp. very 

 large. — ^270, a distorted sp. with one valve overlapping. — 271, 

 another distorted sp. with a large anterior gape. 



93. DiONE CHiONJEA, Menlce* 



Cytherea chionrea, Meiike in Zeit.f. Mai. 1847, p. 190, no. 57. 

 Cytherea squalida, Sow. Proc. Zool. Soc. 1835, p. 23. — Hani. 

 'jDescr. Cat. p. lOi: Wood's Sitpjjl. pi. 13, f. 40.— Sow. Thes. 



Conch, p. 629, pi. 131, f. 87-89.— C. B. Ad. Pan. Shells, 



p. 273, no. 417. 

 Chione squalida, G-rai/ Cat. Ci/th. Anal. 1838, viii. 306. 

 Venus squalida, B. M. Cat. D'Orh. Moll. p. 68, no. 609. 

 Dione squalida, Desh. B. M. Cat. Yen. p. 58, no. 6. 

 + Cytherea biradiata, Gray, Zool. Beech. Voy. 1839, p. 151, 



pi. 43, f. 5. — Slehold. in JViegm. Arch. 

 + Cytherea chione, pars. Sow. Thes. Conch, p. 629, no. 59. 

 P = Cytherea elegans, Kocli. in Phil. Ahhild. Conch. Cyth. 1844. 



p.2(150)pl. 1, f. 4. 



For a full description of the main features of this shell, v. 

 Cytherea chione, Forbes S,' Sanl. Br. Moll. i. 396—8, which 

 applies in most of the minute particulars, even in that which 

 is said to separate it, the 3 short ray-Uke colourless markings 

 of which the central is the shortest, and the others margin the 

 commencement of the lunule and the ligamental area. It is 

 necsssary however to state, for the benefit of those who think 



• The learned have hardly behaved well to this exquisitely ^beautiful species. It 

 was first described from some Peruvian shells of a " very dull and dirty aspect," by 

 Sow., under the name (very inappropriate to the species generally) of C. squalida. 

 He confesses however that" one of the varieties is " rather agreeably ornamented 

 with concentric purple bands." The Mazatlan shells were next described by 

 Gray, in the Zool. Beech. Voy., as C. biradiata, a name appUcable again only to 

 a portion of the species. The East Indian shells were next named by Koch and 

 described by Fhil. in IS 14 as C. elegans. Then Sow. jun. in 1851 gives in quo- 

 tations (as though from the P. Z. S.) a fresh description of C. squahda, with 

 only 6 of the original words, adding with singular inappropriatcness "riibeiite-^ 

 albicante radiata ; cosiellis numerosis, concentricis, obtusis, concinnis, confertis." 

 He also tells us (an error which C. B. Ad. very politely exposes) that the species 

 was first named from Philippine specimens brought by Mr. Cuming ; and also that 

 the name C. biradiata in Beechey's voyage was given to the Philippine shells. 

 Not content with these errors, he also informs us that Mr. Cumings's Mazatlan 

 specimens belong to the Europfean C. chione. — Last of all Menke gives the name 

 C. chionjea to the Mazatlan species; and though he only describes from a single 

 specimen, it fortunately happens that both name and description are sufficiently 

 comprehensive. As the prior names only apply to portions of the species, the 

 ordinary rules of i)riority are disregardedin order to retain an expressive name 

 which includes the whole species. 



