64 



signify). These shells are usually umbilicate (the Australian 

 specimens almost obsoletely) the whorls round with deep 

 spiral sulcations and granular keels. The throat is also 

 grooved, there is a tooth on the columella. Operculum ovate, 

 of comparatively few whorls. All the Tasmanian species 

 are well marked. 



DiLOMA. — Philippi, (Abbild. u. Beschreibungen neuer 

 oder wenig gekannter Conchy lien, Cassel vol. 1. Heft., 8 p. 

 188. Figures and descriptions of new or little known shells). 

 This was only intended as a subgenus by its author, but 

 Messrs. Adams have given it generic value. The distinction 

 is, that the columellar margin does not extend to the outer 

 edge of the labrum, but forms an elevated border or second 

 lip within and parallel to it. But I maintain that this dis- 

 tinction is not of any importance and is shown in many differ- 

 ent genera, especially in TrocJwcochlea, Chloro stoma, Chry- 

 sostoma. There is nothing in fact to separate the species 

 from Adams' TrochococJilea, and I cannot see even a single 

 feature on which a division would rest. It is said that the 

 common Australian and Tasmanian species, D. odontis, Wood, 

 is a smooth shell, but Adams' definition of TrocJwcocJilea is 

 made to include smooth forms. Besides, in this T. odontis 

 varies. Few can be found without distinct spiral grooves, 

 and there is every gradation to a regular carinate form. 

 Biloma ingerrima Chemnitz (the type of the genus ?) might 

 easily pass as a small variety of B. odontis, and the same may 

 be said of B. cetJiiops. Gmelin.* Both are from New Zea- 

 land. I am of opinion that the names should stand Trocho- 

 cochlea odontis, and T. cethiops. The ojDercula of all the 

 Trochocochlea have a peculiar silvery margin which is very 

 characteristic, in this and in the animal T. odontis exactly 

 corresponds with the genus. 



Thalotia.— Gray, 1840 (Synopsis Brit. Mus. Ed. 1842, 

 p. 57, 89, Etymolog. OawSs Wreath ovs ear. Ita. Her- 

 mannsen, who had taken the quotation secondhand from Agas- 

 siz, viz.. Gray himself refers in Guide to Sys. Dist. Moll, to 

 Adams' Genera, showing that he adopts their definition.) The 

 shells of this genus are elongately conoidal, with quadrangu- 

 lar apertures. Columella, straight truncated, tubercular, 

 whorls transversely grooved and granular. It is a well marked 

 Australasian form. 



ZiziPHiNus. — Gray 1840 ( loc. cit., but Messrs Adams 

 give Leach as the author, which is probably the case, as Gray suc- 



* I think that a variety of D. cethiops, has been mistaken for Trochus 

 ni(/errmus of S. America, and this is Von Marten's opinion. 



