608 ON SHELLS FROM THE SOLOMON ISLANDS. [JuUC 2, 



Reeve, and some of them exhibit indistinct spotting and reticulation 

 •when held up between the Hght and the eye. The surface of the 

 brown-black epidermis is without gloss, and under the lens appears 

 finely rugose or subgranidar. The operculum is rather narrow, with 

 a projection on each side in front of nearly the same length, with a 

 deep rounded sinus between, and the horny portion covers about half 

 the surface. 



The figure of the operculum of ^V. cumingiana, giveu by Martens 

 (Conch. -Cab. ed. 2, pi. 4. fig. 4), somewhat resembles it, 



A'', magnijica, Reeve, and N. searabceus of the same author, are 

 the same species, but I doubt whether N. sanguisuga also belongs to 

 it. The sculpture of the former is not quite the same, and the 

 surface more glossy. 



65. Navicella suborbicularis, Sowerby. 



Hah. Faro, Treasury, and Ugi Islands, from streams {Guppy) ; 

 Guadalcanar (/. Macgillivray) ; and San Christoval {Brenchley). 



Both the varieties described by Martens (Conch.-Cab. ed. 2, p. 31, 

 pi. 6. figs. 5-14), and also figured by Reeve (Conch. Cab. figs. 5, 5a), 

 occur in the Solomon Islands, the black-striped variety being 

 apparently of less frequent occurrence than the more finely reticu- 

 lated form. 



66. Unio guppyl (Plate XXXVII. figs. 8-8 b.) 



Shell elongate, very inequilateral, usually a little longer than twice 

 the height, compressed, covered with a blackish-brown epidermis, 

 exhibiting strong lines o! growth and very faint radiatiug substriation, 

 and marked with fine wrinklings at the eroded beaks, which are 

 small and placed quite near the anterior extremity. Dorsal margin 

 behind the umbones almost straight or the least excurved for some 

 distance, then at an obtuse angle becomiLg oblique before rounding 

 into the extremity, which is a little more sharply curved than the 

 anterior end. Ventral outline either faintly excurved, straight, or the 

 least concave. Interior bluish-white, most iridescent at the hinder 

 extremitv, generally stained in parts with olive- brown. Cardinal 

 tooth of' the right valve moderately large, four- or five-lobed at the 

 top, situated just in front of the umbo. Between it and the outer 

 margin is a short ridge, the space between the tooth and the ridge 

 receiving the single, smaller, roughened and striated tooth of the left 

 valve. Lateral tooth of the right valve long, obhquely truncate 

 behind, fitting in between two teeth in the opposite valve. Anterior 

 adductor scar deep, posterior superficial, squarish in front. Pedal 

 scar in both valves under the cardinal tooth very deep. Ligament 

 elongate, prominent. 



Length 80 mm. ; height 38 ; diameter 21. 

 „ 70 mm. ; „ 35 ; „ 18. 



Hub. From streams in Shortlaad Island. 



This species recalls to miud some of the forms from Australia and 

 New Zealand. Its principal features are the elongate compressed 

 form, dark brown colour, wrinkled apices, and coarse incremental 



