272 



The straight, acute margins of the peristome, giving the shell 

 an Achatinoid aspect, so different from typical Ena, are a 

 character sufficient, in my opinion, to warrant the retention of 

 the group as a separate genus, and I therefore follow Bour- 

 guignat's lead in this respect. 



The radula closely approximates that of Ena obscura, according 

 to Schacko *. A specimen of R. punctatus from Tette is reported 

 on by him as follows : Central tricuspid, very small ; laterals, , 

 strong, with a large, obliquely truncate central plate ; marginals 

 very abundant, with 7 side cusps. 



This genus, established in 1889 by Bourguignat, had been uni- 

 versally relegated to the synonymy of Rachis, Albers (Rhachis, 

 Pfeiffer and von Martens), but recently Dr. Thiele t has stated 

 that an examination of the radula of punctatus has satisfied him 

 that this species does not pertain to the latter genus but to Ena 

 in its wider sense. He consequently revives Rachisellus but 

 reduces it to a subgenus of Ena. Although von Martens indi- 

 cated punctatus as the type of the former, at the same time, 

 following in Pfeiffer's footsteps, altering its orthography to 

 Rhacliis, Dr. Thiele points out that as this species was not in- 

 cluded by Albers in 1850 when the section Rachis was established 

 by him, with Bulimus pollens, Jonas, as first species, the latter 

 must be regarded as type. 



241. Rachisellus adumbratus, Pfeiffer. 



Bulimus adumbratus, Pfeiffer, P. Z. S. 1854, p. 291 ; ibid., Mon. 



Helic. Viv. iv, 1859, p. 472; Hanley & Theobald, Conch. Ind. 



1876, pi. 148, fig. 8. 

 Bulimus (Rhachis) adumbratus. Pfeiffer, Malak. Bla'tt. ii, 1856 



p. 161. 

 Buliminus (Rhachis) adumbratus, von Martens, Die Heliceen, ed. 2, 



1860, p. 231 ; Nevill, Hand List, i, 1878, p. 130 ; Kobelt. Conch.- 



Cab., Fam. Buliminidae, 1900, p. 675, pi. 102, fig. 19. 

 Bulimus adumbratus, Nevill, Enum. Ilelic. Ceylon, 1871, p. 3. 

 Bulimina (Rachis} adumbrata, Pfeiffer & Clessin. Nomeucl. Helic. 



Viv. 1881, p. 285. 

 Rachis adumbratus, Jousseaume, Mem. Soc. Zool. France, vii, 1894. 



p. 296. 

 Rhachis adumbratus, Kobelt & Mollendorff, Nachr. Dents. Malak. 



Ges. 1903, p. 37. 



Original description : " T. subobtecte perforata, ovato-conica, 

 solidula, Iffivigata, albido et roseo adumbrata, strigis distant! bus 

 roseo-fuscis et punctis sparsis pellucidis signata ; spira conica, 

 apice acuta, nigra ; anfr. 6 vix convexiusculi, ultimus spira paullo 

 brevior, basi rotundatus, fascia 1 castanea notatus ; columella 

 subverticalis ; apertura obliqua, oblongo-ovalis ; perist. simplex, 



* In Mobius, Beitr. Meeresfauna Ins. Mauritius u. Seychellen, 1880, p. 340. 

 f \Viss. Ergebn. Deuts. Zentr.-Afr. Exp. iii, Zool. 1911, p. 201. 



