364 PROCEEDINGS OF THE ACADEMY OF [1897. 



larger, projecting beyond and closely overlapping the left along the 

 whole basal margin. Both valves have the posterior area defined 

 by a keel. Sculpture rather fine, irregular wrinkles parallel to 

 growth lines, becoming coarser below, and obsolete toward the 

 beaks, where numerous spaced radial cannula;, linear and very del- 

 icate may be seen under the lens. Interior white, the right valve 

 with a high, triangular, recurved tooth fitting into a corresponding 

 deep process in the other valve. 



Length 18"5, height 11, diam. 11 mm. 



Length 17*5, height 11, diam. 9.3 mm. 



Sydney Head (John Brazier), and Eden, Twofold Bay, New 

 South Wales (Dr. J. C. Cox). 



This species is probably the C. nasuta of Angas' lists of Australian 

 mollusks, but it is not, in my opinion, the C. nasuta of Sowerby, 5 

 described from Xipixapi, west coast of Colombia. The latter is 

 smaller, adults before me measuring 7*5 to 10 mm. long, and the 

 beaks are somewhat different. In C. nasuta, as Reeve's figure 

 shows, the larger valve projects above beyond the smaller, while in 

 C. Coxi the two are nearly equal above. In C. nasuta the concentric 

 ribs are more prominent on the anterior end than in C. Coxi. The 

 posterior rostration is decidedly longer in C. nasuta. Sowerby's 

 types measured : long 0*7, lat. # 35, alt. - 4 inch. These differences 

 indicate specific distinction ; the very widely separated habitats of 

 the two forms also pointing in this direction. 



EXPLANATION OF PLATE IX. 



Figs. 1, 2, 3. Corbula Coxi. Lateral, ventral and posterior views. 

 Figs. 4, 5, 6. Adeorbis sigaretinus. Anterior, ventral and dorsal 



views of the shell. 

 Fig. 7. Tatea rufilabris. Front view of shell. 

 Fig. 8. Tatea huonensis. Dentition. 

 Fig. 9. Tatea huonensis. Operculum, from within. 

 Figs. 10. 11. Tatea paradisiaca. Front views of two specimens. 

 Fig. 12. Tatea huonensis. Front view of shell. 



All figures variously enlarged, reproduced from camera lucida 

 drawings. 



5 Proc Zool. Soc. Lond., 1833, p. 35; Reeve, Conch. Icon., Vol. II, pi. 1, 

 fig- 1. 



