I 156 CUISTAOENS 



Cristapkns guppy; (Smith). 



Shell obioni:^ elliptical, very inequilateral, a little higher be- 

 hind, siibsolid. sn1)compressed or convex : beaks not promi- 

 nent, scnli)Uired with a great number of zigzag-radial, wavy, 

 fine ridges, the sculpture extending well on to the disk; sur- 

 face wnth irregular, rather strong, concentric sculpture and 

 faint vestiges of radial grooves ; posterior ridge low\ rounded ; 

 anterior end narrowed and rounded : outlines of dorsum and 

 base nearly straight ; posterior end irregularly rounded, the 

 upper part slightly and obliquely truncate ; epidennis thick, 

 reddish-l>rown, peeling oft' behind showing the iridescent shell ; 

 pseudocardinals small, often split into numerous denticles; 

 laterals small, remote, straight ; anterior scars impressed ; 

 nacre bluish-white, bronzy iridescent liehind, thicker in front. 



Length 69, height 32, diam. 19 mm. 



Length 67, height ^:^, diam. 15 mm. 



Shortland Island ; Solomon Islands. 

 Unio gnppyi Smith, Pr. Zool. Soc. Lond., 1885. p. 608, pi. 



xxxvn, figs. 88a, S8b. 

 Ctenodesma gnppyi Simpson, Syn., 1900, p. 853.— Haas, Con. 



Cab., Unio, 1910. pi. xiii, figs. 6-7. 



The above measurements are from two fine specimens in the 

 National Museum collection from the Solomon Islands. The 

 whole surface shows a tendency to feeble granulation. 



Cristadens beauforti (Eavay). 



■'Shell irregularly elliptical, slightly inflated, not very thick, 

 beaks placed quite anteriorly ; anterior end short, truncate and 

 rounded, posterior end elongated, rounded and compressed 

 above, angulate below, ventral margin almost straight, slightly 

 curved in the middle ; a very large ridge extends from the 

 beaks to the lower posterior angle ; epidermis heavily striate 

 in front and behind, smoother in the centre of the disk. Car- 

 dinal teeth weak, short, that of the right valve bifid ; laterals 

 long and thin, not extending beyond the ligament, the right 

 slightly prominent, the left bifid. Epidermis bronzy, greenish- 

 black ; nacre bluish-white. 



Length 70, height 37, diam. 20 mm." (Bavay). 



Type locality. Lake Sentani, New Guinea. 



