

436 Transactions. 



p. 756, 1758) the species Trochus maculatus Linne (Proc. Mai. Soc. (Lond.), 

 vol. x, p. 225, 1912). 



The genus Tectus Montfort is well defined and limited, and does not occur 

 on the mainland of New Zealand, but the shell I described from the Ker- 

 madecs as Trochus royanus (Proc. Mai. Soc. (Lond.), vol. x, p. 225, pi. ix, 

 fig. 12, 1912) must he called Tectus royanus (Iredale). 



Infundibulum Montfort does not easily fall into any other group, and 

 should be generically recognized, but no members are Neozelanic. Gar- 

 dinalia Gray constitutes another distinct little group, whilst Trochus niloticus 

 cannot be easily lumped. 



The majority of the other species can be classed around Trochus macu- 

 latus Linne, the type of Trochus Linne, 1758, of which Lamprostoma Swain- 

 son, 1840, is an absolute synonym. Fischer's Coelotrochus and Gray's 

 Anthora seem merely .sections of this genus, and scarcely seem worth recog- 

 nition. The species seem to grad*: very easily. If the section " Anthora " 

 be retained, a good excuse being the. thickened outer lip, a rather infrequent 

 occurrence in the genus, it must be renamed, as Anthora Gray is preoccupied. 

 The new name Thorista can be used. The species Polydonta chathamensis 

 Hutton, 1873, does not fall into any known Trochoid group, and it is worth 

 while noting that the species is placed under the genus Gibbida (sensu latis- 

 simo) in the British Museum. Suter has associated subspecifically the 

 shell he described as Trochus. oppressus var. dunedinensis, and " Trochus " 

 oppressus was described by Hutton under the genus name Gibbula. To 

 fix the valid nature of this group it is only necessary to state that on p. 144 

 Suter has included the species described by E. A. Smith as Calliostoma 

 aucklandicum. in the genus Calliostoma, with the remark, " I have not seen 

 this species." Examination of the types of Smith's species show them to 

 be very close allies of " chathamensis," and I see that in the " Hab." of 

 that species " Auckland Islands (Captain Bollons) " occurs. Specimens 

 from Snares in 50 fathoms (Captain Bollons) and Bounty Islands in 50 

 fathoms (Captain Bollons) appeared to agree with the Auckland Island 

 shell. From the series here available, I conclude the two forms are dis- 

 tinct, and the above localities should be transferred from " chathamensis " 

 to "aucklandicum." 



Inasmuch as the three selections Trochus, Gibbula, and Calliostoma are 

 each unsuitable, and show the peculiar nature of the shells, I introduce the 

 new genus Thoristella, and designate Polydonta chathamensis Hutton, 1873, 

 as type. The subfamily name is spelt in error on p. 106 " Trochininae" ; 

 it should be " Trochinae." Trochus will be retained, as the New Zealand 

 species are congeneric, with T. maculatus Linne. 



The names to be used would be,— 

 Genus Trochus Linne, 1758. 



Section Coelotrochus Fischer, 1880. 



Trochus tiaratus Quoy and Gaimard, 1834. 

 Section Thorista nov. = Anthora Gray preocc. 

 Trochus viridis Gmelin, 1791. 



camelophorus Webster, 1906. 



Genus Thoristella nov. 



Thoristella chathamensis (Hutton, 1873). 



— var. dunedinensis (Suter, 1987). 



aucklandica (E. A. Smith, 1902). 



oppressa (Hutton, 1878). 



