181 



ON SULCOBASIS CONCISA (FEB.) AND ITS NEAREST ALLIES. 



By C^SAR K. BOETTGKK. 



Bead 12th June, 1914. 



PLATES lY, V. 



In working out a collection of shells from the Aru Islands, it became 

 evident that the Sulcobusis of the concisa group from these islands, 

 liitlierto usually referred to r^ibra, Alb., is quite a different form. 

 Tlie whole group was therefore critically examined, with the following 

 results. 



The species to be discussed are concisa, Fer., rubra, Alb., and cumingi, 

 Gude. It has been thought important to examine, as far as possible, 

 the actual specimens described by the various authors, and thus to 

 determine their correct status. Indeed, it is surprising how scanty 

 the material is on which, the authors based their descriptions, for the 

 collectors who visited the habitats of these shells only brought home 

 single specimens, and consequently they are of the greatest rarity in 

 collections. I have been fortunate enough to study and to compare 

 nearh' all the specimens quoted in literature. This investigation 

 shows that, though subspecifically different, they agree in so many 

 characters that they must be considered to belong to oidy one species, 

 wliich, according to priority, must be called Sulcobasis concisa (Fer.). 

 This species, which is also well defined from a geographical point of 

 view, may be divided into three sub-species. 



The general diagnosis of S. concisa {Ydr.), as restricted by me, runs 

 as follows : — 



Testa umbilicata, plus minusve depressa, solida, unicolor rufa aut 

 rufo-castanea, striis incrementi regulariter striata, fere Isevis, aut 

 sulcis numero variis, plus minusve distinctis, obliquis, irregularibus 

 incisa ; spira conoidalis, aut subdepressa aut planiuscula ; sutura 

 impressa. Anfractus 6, convexiusculi aut convexi, regulariter 

 accrescentes ; ultimus rotundatus, antice plus minusve descendens, 

 ad aperturam dilatatus ; umbilicus pervius. Apertura obliqua, 

 obovalis, intus alba, ])orcellana, colore externo translucente ; peristoma 

 vix incrassatum, album, reffexum, marginibus callo albo, arcuato 

 junctis, columellari dilatato. 



The three sub-species of the shell, known up to date, are : 

 1, S. concisa rtibra (Alb.) ; 2, S. concisa concisa (Fer.) ; 3, aS'. concisa 

 camingi (Gude). 



1. Sulcobasis concisa eubra (Alb.). PI. IV, Fi<;s. 1-12. 



1857. Helix [Chloritis) rubra, Alb. Albers, Malak. Bliitt., Bd. iv, 

 p. 93, Taf. ii, figs 1-3. Arrow Island? (Coll. Mousson). 



1859. Jlelix rubra, Alb. Tfeiffer, Mon. helic. viv., vol. iv, p. 287. 



Arrow Island (?). 



1860. Helix ( Chlnritis) rubra, Alb. Albers, Die Heliceen, 2. Ausgabe 



von Eduard von Martens, p. 162. Arrow Island. 



