NO. 1237. SYNOPSIS OF THE LUCINACEA— BALL. 797 



but is Pohmesian. The references to west-coast localities are prob- 

 ably based on Codahia colpoica Dall. Z. pxtvetata of Poulsen's cata- 

 logue is probably L. orhicularis Linnteus. The Diplodonta semiaspera 

 of Carpenter in the Mazatlan catalogue was a compound of several 

 species. His variety discrepant is indeterminable. A pencil sketch 

 of it in my possession, made by Carpenter, looks not unlike the young 

 of Diplodonta orbella Gould. 



Family LUCINID^E. 



This family differs from the Diplodontidm by its less perfectlj^ devel- 

 oped gills; from the Thyasiridce by the inclusion within the general 

 mass of the bod}^ of the hepatic and sexual glands, and also by the 

 gills being less developed; from the Corbidw by the general shell char- 

 acters and the loriform anterior -adductor scars prolonged into the 

 area of the disk. The branchial orifice is usually incomplete, and the 

 anal is supplemented by a greatly developed introvertible tube, cor- 

 responding to the "valve" of an ordinary Teleodont siphon, and usualh^ 

 supposed to be, but actuall}^ not, homologous with a true siphon. If, 

 as seems possible, the Silurian Prolucina is a true Lucinoid, this is one 

 of the few families of Teleodonta which are represented in the Silurian, 

 but the characteristics of Prolucina are not j^et fully elucidated. 

 Excluding pre-Tertiary groups, the family contains the following 

 genera: 



CODAKIA Scopoli, 1777. 



LUCINA Lamarck, 1799. 



LORIPES Cuvier, 1817. 



MYRT^^A Turton, 1822. 



PHACOIDES Blainville, 1825. 



DIVARICELLA von Martens, 1880. 



These groups and their su])divisions will be taken up serially. 



Genus CODAKIA Scopoli. 



This is Codahia Scopoli, 1777; Orhicahm (sp.) Megerle, 1811 (not 

 Orhicida Lamarck, 1799); Lentillaria Schumacher, 1817; Lenticvlaria 

 Gray, 1847; Ciena Morch, 1800 (not Ctenia Lepel, et Serv., 1825, 

 Lepidoptera)^ Jagonia Recluz, 1869; Ant ilia de Gregorio, 1885 (not 

 ^1;^ ?'////.'/ Duncan, 1864, Corallia)\ (7(9^«A'«'« Fischer, 1887, \xx\d Lintellaria^ 

 Bucquoy, Dollfus, and Dautzenberg, 1898 {err. typ. pro Lentillaria). 

 This is a well-marked genus which may be divided as follows: 

 Codakia s. s. Shell large and heavy with more or less distinctly 

 reticulate sculpture, valves white externally, if colored the color is 

 internal and chiefiy marginal; with small beaks and lunule, not intiated, 



