650 PROCEEDINGS OF THE ACADEMY OF [DeC.^ 



spiral lineolation. The sculptured form is evidently more primitive, 

 the derivative smooth forms being different in the two rivers. 



"Three similar shells were received from the Rio Jamauchim, an 

 affluent of the Tapajoz on the right side. The smooth phase is here 

 light citrine with greenish-black lines in the grooves, and the sculp- 

 tured phase is somewhat larger. See PI. XXIV, figs. 8, 9. A quite 

 young shell of the sculptured form is honey-yellow, with very few 

 small black spots. 



"Doryssa transversa, var. near macapa Moric. PI. XXIV, figs. 13, 14. 



"This form has very strong sculpture. Spiral grooves 6 or 7 on 

 each whorl of the spire. Microscopic spirals weak or wanting on the 

 last whorl. Axial folds strong, slightly curved, a little protractive, 

 on the last whorl straight or sigmoid. Color russet, indistinctly 

 variegated with black streaks or bands. 



"Length 44.5, diam. 16 mm.; 7 whorls remaining. 



"Rio Maccuru, four specimens, and a single specimen from the 

 Rio Jar5' probably belongs here. 



"Differs from D. macapa by the truncate top and better-developed 

 sculpture, but seems too near that for separation. It is doubtless 

 "a form of the polymorphic transversa. 

 "Doryssa inconspicua Brot. 



"Conchylien Cabinet, p. 355, figs. 2, 2a. 



"Nine specimens come from the Ilha de Goyana, Rio Tapajoz, 

 nine from the Rio Maccuru, and one from Tucunare on the Rio 

 Jamauchim. 



"The species is perhaps distinct by its small size, etc., but it is 

 very near some forms of transversa. 

 "Doryssa rex Pilsbry, n. sp. PI. XXIV, figs. 10, 15. 



"Shell large, tapering to a narrow truncation. Spiral grooves 

 about 6 on the whorls of the spire, becoming wider on the last whorl, 

 where the intervals are coarse and cord-like. Microscopic lineola- 

 tion obsolete. Axial ribs slightly protractive, irregular, or obsolete 

 on the last half whorl, about 12 on the penultimate whorl. Upper 

 whorls nearly flat. Suture deepening on the last whorl, which is 

 produced in a prominent keel defining a broad, horizontal shoulder 

 below the suture, as in D. devians Brot. Color dull olive-citrine,. 

 in places passing into chestnut. 



"Length 71.5, diam. 28 mm.; 7| whorls remaining. 

 " 67, " 24.5 " 7h " 



" 73, " 27.5 " Sf " 



