149 



oblique striata; apiee obtu.$o ; anfr. 4, rapide crescentibus, convexis, 

 decUvibiis ; apcrtura spira ceqitanti, ovata, 2'>oft>ce angii^fa, labro acuto, 

 labio incra^sato, conspicuo. Long. 3, lat. 2 mil. 



Shell minute, ovate, subumbilicate, thin white, subpellucid, 

 finely and regularly lirate all over and obliquely transversely 

 striate ; apex obtuse ; whorls 4, rapidly enlarging, convex, 

 sloping ; aperture equalling the spire, ovate, narrowed pos- 

 teriorly, outer lip acute, inner lip thickened, conspicuous. 

 Long Bay, Eev. H. D. Atkinson, 



No. 50. ScissuRELLA ATKDcsoyi. U.S. S.f. parvu, feuiH, palUde lutea 

 vix transhicida, haud nitente, oblique suborbiculari, ad basim dilatata, 

 spira minus ex-serta sed aliquantulum complanata ; anfr 4, vix, convexis, 

 rapide crescentibus, superne fasciatis, tenuiter cancellatis, basim versus 

 subcai'inatis (liris longitud. subfasc. declivis, supi-a curvatis) ; sinu incon- 

 spicuo, fascia sinus prominente, marginibus elevati.% longitrorsum distanter 

 arcuatim retrorsimque Uratis ; fssura elongata, antice attenuata non longe 

 ab ore perforante ; aperfura, orbiculari simplici : labro acuto ; labio sub- 

 re/exo, curvato ; infima facie cavum infundibulifor.ferentf. Long. 2, 

 lat. 1 mil. 



This most interesting shell is the first of the genus found 

 in Australian waters. It was dredged from a sandy bottom 

 at six to ten fathoms by the Eev. H. D. Atkinson, and 

 Blackman's Bay, W. F. Petterd. After a careful comparison, 

 I must say that the species is so near the British S. crispata 

 that the differences are almost inappreciable. There were 

 only three specimens seen by me, and in all these the slit was 

 closed, and the sinus not perceptible on the lip. The fascia 

 of the sinus does not extend to the two last whorls of the 

 spire. Prof. Moriis in his observations on this genus (Moll. 

 Great Oolite, Palaeontograph Soc, 1854, p. 81), accounts for 

 the foramen by supposing the animal to keep the siphon 

 stationary during a considerable period of the formation of 

 the shell matter in advance. He says : " When the animal 

 was forming new shell in advance of the aperture, the fissure 

 was not advanced forward with it, but the anal syphon 

 remained in the same position until a considerable progress 

 had been made in the formation of new shell. At length that 

 organ was withdrawn to be protruded from the aper ure 

 and the formation of a new fissure immediately commenced." 

 In this state it shows that the genus Trochotoma would be a 

 Pleuroto))iaria. Both genera have been rather arbitrarily 

 separated from Scissurella and from each other. In the three 

 specimens submitted to me one had the outer lip broken, and 

 the fissure then was like a Pleurotomaria. I separate the 

 Tasmanian species from the British one only to promote 

 further investigation. There is no difficulty in supposing 

 them identical, as we have other instances of British species 

 appearing in Australian seas, while they are utterly unknown 

 in intermediate seas. In the same way in our flora we have 



