robson : mollusca on the dogger bank. 175 



Lamellibranchia. 



Living. Empty shells. 



Gari ferroensis (Chemn.). Mactra solida, Linn. 



Mactra stultorum, Linn. Cardium edule, Linn., and sp. 



Venus gallina, Linn. Astarte sulcata (Da C). 



Spisula suhtruncata (Da C). Dosinia exoleta (Linn.). 



Donax vittatus (Da C). Liccina borealis (Linn.). 



Tellina fabula, Gron. Lu^inopsis undata (Penn.). 



Nucula nitida, Sby. Lutraria elliptica (Lamk.). 



Ensis ensis (Linn.). Cyprina islandica (Linn.). 



Cultellus pellucidus (Penn.). Tdlimya ferruginosa (Mont.). 



Pecten opercularis (Linn.). 



Syndosmya prismatica (Mont.). 



Ensis siliqua (Linn.). 



It is impossible to give a complete list of the members of other 

 groups associated with these mollusca, but the following forms 

 were found fairly constantly in the hauls throughout the area : — 



Nephthys cceca (MtilL). 



Lanice conchilcga, Pallas (empty tubes only). 



Goniada maculata, Oerst. 



Magelona papillicornis, Miill. 



Sigalion mathhildcB, Aud. 



Baihyporeia pelagica (Bate.). 



Ampelisca Icevigata, Lilljeborg. 



EcJiinocardium cordatum, Gray. 



The large quartzite boulder referred to above had a special fauna 

 of its own, which in variety and number contrasted very markedly 

 with the poverty of the sandy bottom. Upon it were found five 

 Hydroids {Tuhularia sp., Gonothyrcea gracilis, Sars, Ohelia dichotoma 

 (Linn.), Calycella syringa (Linn.), Filellum serpens (Hass.)), three 

 Polychsetes, Flustra foliacea (Linn.), Eolis sp., Buccinum (egg 

 capsules), Ophiothrix fragilis (D. &K.), Balanus sp., and a Tunicate 

 {Styelopsis grossularia (van Ben.)). This boulder was found upon 

 a remarkably sterile patch of gravel. 



The list of mollusca given above contrasts very remarkably with 

 other lists that have been published in the past. The Dogger has 

 usually been regarded as a malacologist's El Dorado, and in the 

 most exhaustive list ^ published are recorded seventy-six species of 

 Gastropoda and fifty-eight of Lamellibranchia. As against this, we 

 have as thfe result of six days' intensive work on the South-west 

 Patch no more than ten Gastropod species and twenty-one Lamelli- 

 branchia, or only 23 per cent of the total recorded by Hargreaves. 

 The contrast becomes more marked if we consider the Gastropoda 

 alone ; for of these only 13 per cent of Hargreaves' records were 



^ Hargreaves, Journ. of Conch., xiii, 1910, pp. 80, 99. 



