5r Mollusca from Juan Fernandez. Addenda. 



By 

 NILS HJ. ODHNER, 



Stockholm. 



Since the publication of my report on the mollusca of Juan Fernandez 

 and Easter Island, forming No. 22 in the Series of Zoological papers edited 

 by Prof. Skottsberg, some additional material of cephalopods has been 

 handed over to me for identification; it deserves to be published for completing 

 the list of mollusca from this interesting tract. In the present note these 

 species of cephalopoda are reported; they were collected by the same Swed- 

 ish Pacific Expedition 1916 — 17 by Mr. K. Backstrom. In this connection 

 it may be mentioned that in another paper I have dealt with some few forms 

 from Masatierra collected during an earlier visit to Juan Fernandez by Prof. 

 Skottsberg, viz. in 1908.^ For the sake of completeness I give in this 

 account a brief survey of the species recorded in that paper. One of them 

 was described as new, viz. Marinula juanensis, and proved a close relation to 

 a West American species of the genus Pedipes [P. unisiilcatus from Mexico). 

 The remaining mollusca reported were marine gastropoda of the following 

 species: Helsioniscus ardosiaeus Hombr. & Jacq., Diloma nigerrima Gmel. and 

 Littorina mauritimia Lam., the last recorded also in my first report. Diloma 

 nigerrima was not previously known from Juan Fernandez. Also the two ce- 

 phalopods mentioned below are accessional to its moUuscan fauna. 



Octopus vulgaris Lamarck. 



One specimen (cT) with a total length of 60 cm (whereof body and head 

 10 cm) was captured at Masatierra the ^'/^ 1917, another ($), 53 cm 

 in length (whereof body and head 18 cm), was captured the ^^/a 19 17 at 

 Masafuera. 



There is no doubt that these specimens belong to Octopus vulgaris Lam. 

 They show the characteristic dermal warts, the 3 supraocular cirri and the 4 

 dorsal ones arranged in a rhomb. The suckerless end of the hectocotylized 

 arm is very short, equal in length to the adjacent part of the arm which bears 



' N. Hj. Odhner, Marinula juanensis n. sp., nebst Bemerkungen iiber die Systematik der 

 EUobiiden. Aikiv f. Zoologi (K. Sv. Vet. Akad.), Bd 17 A, No. 6. 1925. 



