Buccinidæ. 



Af denne Familje har Expeditionen bragt tilveie et 

 Materiale af en ganske betydelig Størrelse, og da det er 

 samlet under en gradvis Fremtrængen fra 60de til 8Ude 

 Breddegrad og ligeledes under en stor Vidde fra Øst til Vest 

 (fra Jan Mayen til heuimod Novaja Semlja), kaster det et Lys 

 over Arternes Variation under de forskjellige geografiske 

 Forholde, der er af stor Interesse. De talrige levende 

 Exemplarer har ogsaa givet en rig Anledning at undersøge 

 den saa meget paaagtede Tandstrukturs Stabilitet. I en 

 lille Atbandling -'Ueber die Varia tionen der Zahnstructur 

 hei dem Genus Buccinum" (Jabb. d. Mal. Grgsell. 1879) 

 paaviste jeg. at der hos Buccinum ikke tør tillægges land- 

 formerne stor Betydning som Artskar akter. I det følgende 

 vil det ogsaa vise sig. at inden Neptio/cti yder denne Karakter 

 lidet tilfredsstillende Holdepunkter, men saa slemt som hos 

 den anden Slægt er det dog ikke. 



Uagtet det saaledes temmelig negative Resultat, som 

 Undersøgelserne af Tandstrukturen har bragt til Gunst for 

 Arterne, saa maa jeg dog indrømme denne Karakter den 

 største Betydning for Classificationen, men før man kan 

 gjennemføre en frugtbringende Revision med Tandstruk- 

 turen som væsentligt Grundlag, er det nødvendig at have 

 fold Oversigt over Formerne. Hos Familjen Buccinidæ er 

 der endnu neppe nok gjort tilfredsstillende Undersøgelser 

 til, at man med fuld Tryghed kan bevæge sig. Der er 

 vistnok al Sandsynlighed for at flere Slægter, saasom 

 Troschelia (Mørch) og Jumala n. gen. ikke vil beholde sin 

 Plads under Buccinidæ, (hvad den første Slægt angaar, 

 da har ogsaa Prof. Gr. 0. Sårs o. fl. tidskilt den og placeret 

 den under Fassiolariderne ; den sidste burde da med samme 

 Ret sættes under Columbella eller Buccinopsis), men for- 

 uden disse to er der ogsaa Pyrolofusus, Volutopsis, Mohnia 

 samt en Art af Siphonorbis, der ikke lader sig indordne 

 under den Ramme, som Troschel har draget for Familjen 

 Buccinina, nemlig: Centralpladen 4 til 7 og Sidepladen 4 

 eller 3 Tænder (Gebiss d. Schuecken Vol. 2, Pg. 69); thi 

 de har alle kun 2 Tænder paa Sidepladen og for Mohnias 



Buccinidæ. 



For the study of this family of mollusca. the Nor- 

 wegian North-Atlantic Expedition has been fortunate in 

 securing a rich collection of materials, which, obtained as 

 it was by the gradual exploration of a tract stretching from 

 the GUtli to the 8(Jth parallel of latitude, and east and 

 west from the island of Jan Mayen almost to Novaja. 

 Zemlja. cannot fail, by the disclosure of many interesting 

 data, to throw light on the varying character of the species 

 under different biological conditions. The numerous living 

 specimens have also furnished ample opportunity of investi- 

 gating the stability of the dentition, to wj*ich attention 

 has been so largely directed. In a brief Memoir, be- 

 aring title: — -'Heber die Variationen der Zahnstructur bei 

 dem Genus Bucciniwi" (Jahrb. d. Mal. Gesell. 1879), I 

 have pointed out. that but little weight, in Buccinum, 

 can be attached to the structure of the teetb as n specific 

 character. In Neptunea, too, as will afterwards appear, 

 diversity of dentition affords anything but a trustworthy 

 guide, though certainly less deceptive than in the foregoing 

 genus. 



But, negative, accordingly, upon the whole, as is the 

 result of research touching the value of dentition in fur- 

 nishing a distinct specific feature, I readily grant to that 

 character the greatest importance in facilitating classi- 

 fication. Meanwhile, a thoroughgoing revision, specially 

 founded on the structure of the teeth, implies an intimate 

 knowledge of the forms. Now. the family Buccinidæ can 

 hardly as yet have been sufficiently investigated to give a safe 

 footing for systematical arrangement to clear up every doubt- 

 ful point. Several genera, such as Troschelia (Morcb) and 

 Jumala, n. g., will, most probably, in future, cease to rank 

 under Buccinidæ; indeed, Professor G. O. Sars and other 

 naturalists have already excluded the former, placing it 

 under Fassiolaridæ, and the latter may with equal reason 

 be classed under Columbella or Buccinopsis. Exclusive, 

 however, of the two aforesaid genera, those of Pi/rolofusus, 

 Volutopsis, Mohnia, and a species of Siphonorbis, cannot be 

 brought within the limits defined by Troschel for the family 

 of Buccinina, viz : — the central plate with from 4 to 7 cusps, 

 and the laterals with 4 or 3 cusps (Gebiss d. Schnecken, 

 Vol. 2, p. 69); for they have all 2 cusps on the lateral 



