Shell light, small, slender, with flat-sided whorls. Protoconch with two and a half whorls, sometimes a little more, relatively broad, with a nucleus irregular at the beginning and with a diameter of 0,17 mm; the diameter of the first whorl is 0,30 mm. This first whorl is sometimes (but not always) a little more prominent than the second. The suture is a little deep and mere is a depression under it. It has a brillant brown colour and lacks sculpture except the nucleus. The three spiral cords appear abruptly at the beginning of the teleoconch. The teleoconch is slender with about six whorls increasing in size a little more quickly than the species mentioned before; flat profile, inconspicuous suture; under magnification, may be seen the colour darker on the protoconch, on the first whorls of the teleoconch and on the base; on the rest of the shell, the colour is cream or very light brown with long darker axial blotches. Three spiral cords run all over the shell; they are smooth and have the same cream colour with blotches. These cords are practically similar in size and equally prominent, with interspaces also equal. On the second or third whorl appears another cord, smaller, placed above the suture. Axial striae, a little separated, are present in these interspaces. There are five cords on the last whorls. The base is smooth and brown. The aperture is rectangular, with a free edge sharp and a little undulating because of die extremity of the spiral cords.

S. carquejai n. sp. is different from S. carinata which is more slender and straight and has a protoconch with more whorls. S. adamsi has a darker colourand its protoconch is shorter and with a simple suture. S. trilineata has a shorter protoconch with a different suture and two cords at the beginning of the teleoconch which has only three cords on each whorl. S. angolensis n. sp. is bigger and longer and its protoconch has more than three whorls, with tubercles on the first one. S. inchoata n. sp. has a darker teleoconch and its protoconch is lighter with a smooth nucleus. S. parilis n. sp. has also a darker teleoconch and its protoconch has tubercles and a simple suture. 5. deaurata n. sp. has a teleoconch of lighter colour, with a slender profile; its protoconch is white and has a peripheric angle.

Seila carquejai n. sp. has been collected in Baia das Pipas in the South of Angola, this bay being designated as type locality. The specimens were found under rocks in the intertidal zone.