Mollusca from South Africa. 135 



described under tliis latter name, aa Tr. rotula, a very minute 

 species, remarkable for a broad spiral groove on the centre 

 of the body-whorl. This merits more study, and, though 

 not, probably, an A/rodonta, it may have to be removed from 

 Trachycijstis. 



Notes on the Anatomy of Afrodonta, M. & P. : Type A. bi- 

 lamellaris, M. & P. By Lt.-CJol. H. H. Godwin- AusTEN, 

 F.R.S. (PI. VIII. figs. 2-2 c.) 



Locality. Edendale Falls, South Africa. 



Animal. The foot of the animal showed no detail on its 

 surface ; the extremity was not very pointed, but no gland 

 could be made out ; there was indication of a peripodial 

 groove close to the edge of the foot. The radula was 

 got out complete ; it is 0*43 mm. in length, long and 

 narrow. The central teeth are all of the same form and size, 

 on quadrangular plates, a central oblong cusp with small 

 cusps at the base on either side ; the lateral teeth are on 

 narrow oblong plates, with irregular minute cusps, but they 

 are so small it was very difficult to see much of their shape. 

 The formula is 7 . 9 . 1 . 9 . 7 or 16 . 1 . 16, in 85 rows. The 

 jaw was indistinct, and composed of narrow plates set side by 

 side. The two otoliths were observed, touching each other. 

 The form of the jaw and teeth of the radula recall those of 

 genera of the Endodontinaj. 



Trachycystis ordinaria, sj). n. (PI. VII. figs. 8, ^ a, S b.) 



T. testa parva, ovato-conica, profunde et anguete umbilicata, 

 riifo-cornea, undique pcriostraco tenui vcstita ; anfractibus 4^, 

 apicali nitido, laivi, obtuso, coeteris ad suturas iiupressis, undique 

 tcnuissime longitiulinaliter obliquistriatis ; aportura ovato-liinari, 

 peristomatc tenui, marginem apud collumcllarcm triangulatim 

 paullum extcnso. 



Alt. '2, diani. 3"0o nun. 



I lab. Potchcfrftroom, Transvaal, Nov. 24, PJ06 {Miss 

 Livinysto/i). 



Only a third of the size of T. simplex *, M. ^t P., but 

 agreeing with it in some details. 



Trachycystis rutilans, sp. n. (PI. VII. tigs. 9, 9 a, db.) 



T. testa couico-depressa, parva, late et profunde umbilicata, 

 omnino corneo-rutilante ; anfractibus 44, apice ipso mamillato, 

 ♦ Ann. & Map. Nat. Hist. ser. 7, vM. xii. (lf>0.?) p. fi04, pi. xxxii. 



