Shell see the original descriptions as well as TRYON (1884) and STREBEL (1912). The follow¬ing data can be added: the protoconch consists of about 2,5 shiny, smooth whorls, honey brown in colour; the first whorl slightly darker and of 750 um diameter. From the protoconch whorls a series of opisthocline axial ribs start to form, first as thin riblets extending from the top to the bottom of the whorl, becoming stronger and shaped as an inverted C in the second teleoconch whorl where their bases become more globose. Between them small striae can be seen. In the subsequent whorl they detach themselves entirely from the upper subsutural cord which also increases in prominence. In the fourth teleoconch whorl these vestiges of the axial ribs become closer and closer to the lower suture, declining in prominence until they entirely disappear. The following whorls are smooth with an irregular, raised subsutural collar and the whorls are traversed by s-shaped striae. At the same time as the axial riblets form in the third whorl, about 9 radial striae also start to emerge becoming slightly stronger in the following whorls but then decreasing in intensity in the fourth or fifth whorls and thereafter are hardly noticeable.
The shell is a light honey-brown throughout. On the fourth whorl the subsutural colar starts to become lighter, being entirely white in the fifth whorl. In subsequent whorls it can be interrup¬ted by patches of light brown; in the final whorl the two major cords are white interspaced with small brown patches the same colour as the whorl itself and the cords on the columnella are also white.
Size: the shell can reach up to 37.2 mm (BERNARD, 1984).
Remarks: The comparison of juvenile specimens of P. perron with species of the genus Clavatula (type species: Clavatula coronata Lamarck, 1801) show much similarity in the aspect of the opisthocline axial ribs, which tend to disappear with maturity in the subsequent whorls. For this reason it is concluded that there is a stronger relationship between these two genera, than with other genera within this family.
Whilst some authors synonymized P. perron with P. spirata Lamarck, 1816 it must be noted that not only are they morphologically different, but the latter inhabits an area further to the south, being restricted to the Luanda area where it has been found at -5/50 meters.
Distribution: This species inhabits the West African infralittoral coast from Cap Esterias (Gabon) to Ambriz (northern Angola).
Special remarks: The type locality is always related with a holotype or a lectotype. In the present case, the original figures are sufficient to determine the identity of the species and it is not nec-essary to designate a neotype; Pleurotoma perronii was described lacking type locality as confirmed by the label of this holotype in BMNH. If the type locality of the first description is erroneous, and no other is mentioned in the description of the synonymized taxa, it is necessary to give more detailed information. Pointe Noire (Congo) is designated as the type locality being in the center of the known distribution area, as well as a locality mentioned by STREBEL (1912) and the source of our specimens. Our material agrees very well with the figures and the known holotype.
Concerning the correct spelling for the name of this species, it must be perron, which is the first name employed by GMELIN (1791) and which is apparently a name not dedicated to a person. TRYON (1884) stated that Chemnitz employed the common Dutch name "perron" (= flight of stairs, in reference to the profile) and that REEVE (1843), misinterpriting Chemnitz's name to be a personal name, Latinized it to read "perronii".