944 PELECYPODA. \_Eulutnellibranchia. 



lachrymose nodules arranged in a somewhat radial pattern. Surface 

 with uneven growth - lines and impressed rest - marks, sculptured 

 throughout with lachrymose nodules, which are often V-shaped, those 

 along the upper part of the low posterior ridge slightly knobbed. 

 Epidermis dark olive-green, clouded with lighter green, rather dull. 

 Pseudo-cardinals small, subcompressed, granulose, 2 in each valve. 

 Laterals straight, 2 in the left valve, 1 in the right. Muscle-scars 

 small, shallow, and irregular. Nacre bluish, lurid purple near and in 

 the beak cavities, thicker in front. (Simpson.) 



I Length, 67mm.; height, 32mm.; diameter, 14mm. Length. 

 62 mm. ; height, 32 mm. ; diameter, 17 mm. 



Type in the U.S* Nat. Museum, Washington. 



Hob. Waiuku ; creeks near Pukekohe and Henderson. 



Remarks. Apparently allied to D. novce-hollandice, Gray, of Aus- 

 tralia, but smaller, less inflated, and less solid than that species. In 

 D. novce-hollandice the anterior third of the shell is almost destitute 

 of nodules ; in the present species the whole surface is covered with 

 them. (Simpson.) 



This subspecies is nearest to D. aucklandicus, Gray, from which 

 it is distinguished by the parallel dorsal and basal margins and 

 the much more prominent nodulous sculpture. The development of 

 the latter, however, is very variable, being sometimes limited to 

 the median part of the valves. It is always found together with 

 D. aucklandicus. 



4. Diplodon Zelebori, Dunker. 1866. Plate 59. tig. 10. 



Unio Zelehori, Dunker: Frauenfeld, V.Z.B.G. Wien, xvi, 1865 (1866). 

 915 ; Rcise " Novara," Zool., ii, 1867, 15, pi. 2, f. 28 ; M.N.Z.M., 161 : 

 Heclley and Suter, P.L.S. N.S.W., (2), vii, 662; Suter, J. de Conch., 

 xli, 292. Diplodon Zelebori, Dunker: Simpson, Proc. U.S. Nat. Mus.. 

 xxii, 1900, 890. 



Shell oval-oblong, very solid, subventricose, rather compressed 

 towards the base, with a short vertical ridge descending from the 

 anterior part of the beaks, and a much longer oblique ridge extending 

 from the posterior end of the beaks towards the lower part of the 

 posterior end. Beaks swollen, turned forward, with an anterior and 

 posterior angle, concentrically finely ridged, and very often orna- 

 mented with fine zigzag wrinkles ; they are approximate and situated 

 at about the anterior fifth to seventh of the length. Anterior end 

 short; convex, the dorsal margin excavated in front of the umbones : 

 posterior end linguiform, the dorsal margin convex, descending, acutely 

 convex toward the straight subsinuate basal margin. Sculpture con- 

 sisting of fine concentric striae with well-marked, rather regularly 

 spaced rest-marks ; faint radiate strife and nodules are sometimes 

 present. Epidermis more or less shining, thin, pale olive, yellowish- 

 brown to blackish-brown. Interior iridescent under the umbones 

 and around the dorsal and posterior margins, bluish-white, the nacre 



