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subsequent ones are much more elongate, I can detect no denticles, perhaps because the cusps 

 he so close together, as to cover each other in part. 



a>,. 



450 



Fig. 3. Teeth of Radula of Ethalia gitamensc Quoy & Gaimard. 



The shape of the rhachidian tooth differs much from that of Unibonium (Rotella) as 

 figured and described by Troschel (Gebiss der Schnecken, Vol. II, p. 220, PL 21, fig. 5 and 6), 

 for though Troschel says of Rotella elegans, that the rhachidian tooth is: "viel breiter als 

 lang", he says on the contrary of the genus: "Die Mittelplatte ist langer als breit", and in his 

 figures, of which that of R. elegans is somewhat strange and irregular, the median teeth are 

 elongate. Of the measurements he says (I.e. p. 221): "Breite der Mittelplatte 0,0125 mm., 

 Lange derselben 0,03 mm. The shape of the other teeth, which in Umdonium, according to 

 Troschel, have no cusps in the median field, agrees sufficiently, to admit relationship. 



2. Ethalia striolata Adams, var. trilobata Sowerby. 



SOWERBY in: REEVE, Conch. Ic. Vol. XX, Rotella, fig. 20. 

 Pilsbry. Man. of Conch. Vol. XI, p. 460, PL 58, fig. 20. 



Stat. 133. Lirung, Salibabu-island. Up to 36 M. Hard sand, i Spec. 

 Stat. 313. East of Dangar Besar, Saleh-bay. Up to 36 M. Sand. 3 Spec. 



It seems that Pilsbry has not seen this species, as he gives no measurements; of the 

 largest Siboga-specimen they are: 



Diam. maj. 13^3, alt. 87,; apert. alt. 7, lat. 6 Mill. 



3. Ethalia minolina Melvill, var. infralaevior n. var. PL VI, fig. 7. 



Stat. 37. Sailus Ketjil, Paternoster-islands. Up to iS M. Coral and coralsand. 2 Spec. 

 Stat. 66. Bank between islands of Bahuluwang and Tambolungan, south of Saleyer. 8 M. 



Dead coral, Halimeda, Lithothamnion. 2 Spec. 

 Stat. 240. Banda. 9 — 2)^ M. Lithothamnion-bank. i Spec. 



Melvill has described (Mem. and Proc. Manch. Literary and Philos. Soc. Vol. 41, p. 20, 

 PL 7, fig. 24) the type of a new species, allied to E. striolata Ads. from the Persian Gulf, and 

 though the specimens under consideration, differ in some degree from a specimen from that 

 locality, they agree in so many points, that I think it is better to give them only varietal rank. 



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