The « Atlantic Slit Shell » is a gorgeous medium-sized pleurotomatiid endemic to southern Brazil, from around Rio de Janeiro to as far south as the Brazil-Uruguay border. The shell is heavily ornamented by finely beaded coarse spiral cords and numerous flamm.ules, the colouration of which vary from red to brown and the saturation vary from one specimen to another. The characteristic shape of adult shells is formed by the gradual shifr of the whorls being smooth-sided, as in the early teleoconch, to strongly inflated and bulging ones in the later stages. It is locally only uncomm.on and is perhaps the most easily obtainable Atlantic slit shell, although it is very susceptible to erosion and bore-holes, specimens in fine conditon are thus still considerably rare. A carnivorous grazer feeding on sponges, it inhabits sandy to muddy bottoms of rather deep water around -150~300m. Typical shell diameter around 65mm., extremely large specimens are known to exceed 85mm. The spire is variable in height although usually it is usually low; the name Perotrochus notialis (Leme & Penna, 1969) refers to a high-spired form and is now considered to be a junior synonym.

Brazil - Uruguay. Finding location: Cabo de Sao Tome, Rio de Janeiro, Brazil.