ATLANT. DEEP-SEA EXPED. 1910. VOL. III]. 



CEPHALOPODA. 



21 



Otherwise all the rare and peculiar Cephalopoda, 

 which from their organisation I consider as deep-sea 

 forms, were taken by the "Valdivia" as well as by the 

 "Michael Sars" only when large open nets were lowered 

 to considerable depths. This applies to those forms the 

 eyes of which according to my investigation exhibit 

 pigment in the state peculiar to dark surroundings, and 

 the body of which is generally provided with light-organs, 

 very often exhibiting a gelatinous swelling. 



If we examine the list of captures recorded in this 

 report, we find that the Histioteuthidae, Veranyidae, 

 Bathyteuthidae, Cirroteuthidae, and most of the Cranchiidae 

 occur only in deep hauls. It is further noticeable that the 

 larval forms have sometimes been captured in shallow 

 water, while the adult animals have nearly all been taken 

 in the nets lowered to greater depths. 



The facts emphasized as regards the representatives 

 of the Oegopsidae apply equally to a number of Myop- 

 sidae. Among the latter I consider the Spirulidae as 

 pelagic deep-sea forms, having at some length attempted 

 to show this, as well as the single specimen of Rossia 

 caroli. Among the Octopoda the Bolitaenidae have 

 representatives which are probably distributed only in 



deep water. Their larvae were only twice taken in nets 

 lowered to 300 m. 



The blind genus Cirrothauma, one of the most 

 precious spoils af the expedition, seems to show that 

 among the Cirroteuthidae there are genera eminently 

 suited to deep-sea life. 



Experience from the "Deutsche Siidpolar Expedition" 

 shows that many fishes and Cephalopoda, provided with 

 light-organs and from their structure probably deep-sea 

 dwellers, arrive at the surface during the night. This 

 applies in no wise to representatives, of all deep-sea 

 families, but only to certain groups. The above mentioned 

 expedition captured Cranchia scabra and Ptery gioteuthis 

 at the surface at night, and it is noteworthy that these 

 very forms were also taken by the "Michael Sars'' in 

 surface hauls during the night, as shown by the lists 

 recording the captures of Cranchia scabra and Pterygio- 

 teuthis Giardi. Besides these we also notice Brachio- 

 teuthis Riisei which on the whole seems to prefer the 

 surface layers. That exhausted or dead pelagic deep-sea 

 forms may arrive at the surface has been emphasized by 

 me before, but the expedition captured none of these. 



