SYSTEMATIC 131 



murrayi (Smith, 1891): South Africa, off Cape of Good Hope, 150 fathoms and Agulhas Bank, 

 40 fathoms; 



aurora Hedley (1916): Off South Australia, 35 55' 30" S, 134 18' 00" E, 1800 fathoms; 



retiolum (Hedley, 1914): Off Green Cape and Gabo Island, New South Wales, Australia, 50-100 

 fathoms ; 



laudandum Finlay (1926) : New Zealand, Otago Heads, 40 fathoms (type) ; Auckland Islands ; Ninety 

 Mile Beach, North Auckland. 



With these additional records for the genus the probable routes of dispersal become more evident. 

 Thus the western coasts of the Americas are considered to have extended the range of this southern 

 genus to the North Pacific via California, Alaska, the Aleutian Chain and thence southward to Japan. 

 The Australian and New Zealand occurrences no doubt had their origin in the Subantarctic rather than 

 as a further southward extension from Japan. The 'Challenger' record ascribed to cancellatus from 

 Marion Island is strongly suggestive of the former supposition. This and the South African occurrence 

 indicate an Atlantic-Indian Ocean cross-ridge source which is supported by the recently reported 

 occurrence in South African waters of Parmaphorella and Glypteuthria, both of which are characteristic 

 Magellan genera (see Tomlin, 1932, pp. 163-4). 



THE BUCCINACEA 



The whelks are a vigorous, highly plastic group of world-wide range, but especially diversified in the 

 polar regions of both hemispheres. 



In 1929 (pp. 57-9) I proposed a classification based largely upon radula and opercula characters, and 

 advocated the use of four families : the Buccinidae, Neptuniidae, Buccinulidae and Cominellidae. Further 

 consideration, however, indicated that the classification I proposed is not nearly so clear-cut as could 

 be desired. Thiele (1929, pp. 305-19) grouped all the genera, covered in the following discussion, in the 

 Buccinidae without the use of either subfamilies or sections. 



However, none of the antarctic and subantarctic whelks appears to have much in common with the 

 northern Buccinum, which has an ovate operculum with a median submarginal nucleus, and a radula 

 with more than three cusps on both the central and lateral teeth. The southern whelks have the 

 operculum either leaf-shaped with a terminal nucleus or ovate with a paucispiral subterminal nucleus. 

 They appear therefore to be derivatives of the Neptuniidae rather than of the Buccinidae. 



Considerable radiation in form has taken place in the southern whelks, making necessary the employ- 

 ment of a series of genera. Not one of these genera, however, is closely similar to Neptunea, and I prefer 

 to consider them members of a characteristic southern family, the Buccinulidae. The chief characteristics 

 of the Buccinulidae are the tricuspid central tooth and an operculum with a terminal or subterminal 

 nucleus. Diversity in the form of the lateral teeth, however, suggests the following subfamily grouping : 



A. Cominellinae (central tooth tricuspid, lateral teeth bicuspid). Pareuthria, Tromina, Notoficula, 

 Falsimohnia* and Glypteuthria* Correlatives are Cominella and Fax, New Zealand and Australia, 

 Phos, tropical Pacific and Searlesia, North-west America. 



B. Buccinulinae (central and lateral teeth tricuspid). Chlanidota, Pfefferia, Neobuccinum, Pro- 

 buccinum, Cavineptunea and Bathydomus. In the last mentioned, the central tooth has an incipient cusp 

 on each side of the central three and the middle cusp of the laterals is split into two or three small cusps. 

 The sum of characters, however, indicates the genus as a near ally of Chlanidota. Correlatives are 

 Buccinulum, Aeneator and Verconella, New Zealand, Austrosipho and Berylsma, Australia, and Kelletia, 

 California. 



* In Falsimohnia the central tooth has the cusps reduced to one and in Glypteuthria a third incipient cusp on the laterals 

 results from bifurcation ; otherwise they closely resemble Pareuthria. 



