292 ZOOLOGY. 



from which I should judge that, like the buckler of the 

 sucking-fish, their function in a great measure depends 

 upon solely mechanical causes. 



A second species, which we also obtained in the 

 Pacific, resembled the above in size and form, but its 

 two long tentacles were furnished at their extremities 

 with rows of suckers, (acetabulaj instead of horny 

 hooked appendages. The prevailing colours of this 

 species are silver-white and steel-blue, spread with red 

 spots and tints of violet and purple, a brilliant and 

 very beautiful spot of emerald-green being placed im- 

 mediately above each eye. We noticed examples of 

 this family of Cephalopods from the Equator to lats. 

 34<> N. and 16 S., Pacific Ocean. 



ARGONAUTA RUFA, Owen. 

 (Ocyth'6e, Sp.J 



We obtained many specimens of this remarkable 

 testaceous cephalopod near the surface of the sea, in 

 several parts of the Pacific, from the Equator to 

 lat. 40 S. 



The shell is a small univalve, of a brown colour, and 

 very elegantly formed in the manner usual with the 

 Argonaut tribe. The contained animal has a short 

 round body, and is speckled with red spots. It has 

 eight arms, two of which are longer than the others, 

 and furnished at their extremities with a membranous 

 expansion, which has been called a (f sail ;" but, since 

 it also obtains in many cephalopods that have no bark 

 to waft, as Loligo, &c., it can have no exclusive use 

 which will sanction the application of that term. 



The animal corresponds perfectly, in size, with the 

 shell it inhabits : its arms accurately filling the aper- 

 ture, or valve, and presenting their surface of small 



