6 ANNALES DE L'INSTITUT OCÉANOGRAPHIQUE 



These two experiments show that the dredge and the bottom-sampler give different 

 pictures of the animal life on the sea-bottom, especially with regard to the quantity of 

 the ditlerent species; the dredge is very liable to miss what is buried in the bottom, 



Comparison between the contents of dredge and bottom-sampler. 

 Southern Kattegat. 



Exp. N° i. Kxp - N ° 2 - 



N. of Raageleje; depht 22 m. — August iS, 1912. N. of Raageleje, depht 28 m. — August i5, 1912. 



BOTTOM : 

 Sand and detritus. 



Macotna calcarea 



Maclra solida 



Cvprina islandica 



— juv 



Axinus tlexuosus 



Nucula tenuis 



Neptunea antiqua 



Buccinum undatum 



Natica pulchella 



Aporrhais pes pelecani. . . 

 Cylichna cylindracea 



Aphrodite aculeata 



l.epidonotus squamatus.. 



Ancia armiger 



Nephthys sp 



Pectinaria auricoma 



Amphitrite cirrata 



Sabellidse 



Amphiura filiformis 



Ophioglypha albida 



— texturata 



Astropecten Mulleri 



Solaster papposus 



Asterias rubens 



Kchinocardium cord 



Strongyloc. drœbakiensis. 



Eupagurus Bernhardus.. . 



Bottom- 

 sampler 

 5 proofs à 



0,2 m " — l mt 



Number 

 of animals 



(calculated) 

 on jo m *. 



Dredge 



in 3 minute: 



= c. 75°>*. 



Number of animal: 



» 

 » 

 » 



I 



1 



» 



2 



20 



IOO 

 2 



c. 149 



75 



» 



45o 



i5o 

 375 



» 



» 



» 



75 



75 



» 



i5o 



1 ,5oo 



» 



» 



i5o 



c. 7.500 

 i5o 



525 



c. 11. 175 



5 

 5 

 1 

 i5 

 » 



» 

 1 



» 

 1 

 1 



H2 

 I 

 I 

 I 

 I 



49 

 74 



18 



3n 

 :. 3 % 



BOTTOM : 



Sand and clay with tubes of 



ilaploops tubicola. 



Abra nitida 



Venus ovata 



Cyprina islandica 



Cardium fasciatum 



Leda minuta 



Nucula nitida 



Lima Loscombii 



Pecten septemradiatus... . 

 — sp. 



Buccinum undatum.... 



Natica catena 



Aporrhais pes pelecani... 



Dentalium entalis 



Chiton sp 



Aphrodite aculeata 



Glycera sp 



Nephthys sp 



Eumenia crassa 



Maldanidas 



Pomatoceros 



Nemertini 



Ophiopholis aculeata. . .. 



Amphiura Chiajei 



— filiformis 



Ophioglypha albida 



robusta 



Strongyloc. drœbakiensis. 



Haploops tubicola 



liupagurus Bernhardus... 

 Hippolyte sp 



Bottom- 



sampler 



5 proofs a 



o ) l ro, — 0,5™* 



Number 

 of animals 

 (calculated) 



on 75 m V 



Dredge 



in 3 minu'es 



= c. 75»' 



10 

 10 



Number of animals. 



i5o 



» 



i5o 



i5o 



1 .o5o 



i5o 



3oo 



» 



» 



1 

 1 



7 

 •4 



manv 

 » 



c. 57 



i5q 



» 

 » 



c. i.5oo 

 1 . 5oo 



» 

 manv 



» 



i5o 



i5o 



1 .o5o 



2. 100 



8.55o 



2 



5 

 1 



3 

 1 



5 

 3 



24 

 5 

 many 



10 

 » 

 a few 

 1 



» 

 many 

 a few 



'4 



1 



1 



210 



i5 



24 



manv 

 1 1 



1 



340 

 C 4 % 



Fig. 4. 



Lamellibranchs, Annelids, Echinocardium, etc., and to take what is lying on the bottom, 

 rapacious Gastropods, large Crustacea, Strongylocentrotus, rapacious Asteridae, etc.; as 

 already said, if a great many animals are wanted from the bottom of the sea in the 

 shortest possible time, the dredge is the superior apparatus, but if we desire a true 



