283 



BULLETIN OP THE BUREAU OF FISHERIES. 



Material examined— One immature female was taken by the Albatross in 286 to 290 fathoms, station 

 4095, northeast approach to Pailolo Channel [S. S. B. 209]. It is catalogue No. 214378 of the United 

 States National Museum. 



Remarks. — This interesting species has been described in such excellent detail by Verrill, Joubin, 

 and other writers, that I have endeavored in the above paragraphs to give merely an account of the 



more salient characters of the species as they appear in the specimen 

 at hand, and to add an account of the funnel organ which has 

 hitherto remained undescribed. The latter is chiefly interesting for 

 its relatively anterior position and great size, for in general outline 

 it does not specially differ from the usual W-shaped type of organ 

 prevalent in most octopod genera. 



As this species has not hitherto been reported from the Pacific, 

 there would seem to be strong reasons for doubting its identity with 

 the Atlantic A . mollis, if on no other than geographical grounds, yet I 

 have been unable to find any characters which could be used in 

 separately defining it. Perhaps this 

 is due to the obvious immaturity of 

 the present specimen, for an indi- 

 vidual observed by Verrill (1881, 

 p. 420) was nearly 79 cm. in length 

 and weighed over 20 pounds, while 

 a single dorsal arm recorded by 

 Joubin (1900, p. 32) is 161 cm. long. 

 An allied form — .4. pacific us 

 Ijima (see Ijima and Ikeda 1902, 

 p. 87, footnote) — has been described 

 from the Sagami Sea, Japan. The 

 chief character advanced by the 

 author to separate this form from ^4. 

 mollis is simply that the suckers 

 "are arranged in a single row for 

 the greater part of the artn length, 

 being biserially arranged only in the 



free tip." That, unless supported by other structural differences, 

 this feature is of no very weighty importance is readily seen upon 

 examination of the present specimen, for whereas one author might 

 describe the arrangement of the acetabula as unmistakably in two 

 rows, another might as positively assert them to be uniserial. The 

 truth is that, as Hoyle has shown in the case of Polypus (1886, p. 76; 

 1904, p. 18-19), a 'l th e suckers are morphologically to be regarded 

 as ranked in a single row, the component members of which have 

 undergone a greater or less lateral displacement to each side in 

 alternation, the resulting biserial appearance being purely sec- 

 ondary. In this respect Alloposus occupies an intermediate position and hence the claims of 

 A. pacificus to recognition as a good species can not yet be taken as established, even though 

 in the absence of a complete description of the Japanese form it would be premature to unite the 

 two dogmatically. 



Jpite ■ 



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Fig. 12. — Alloposus mollis [209], out- 

 line drawing of funnel laid open 

 medioventrally to expose funnel 

 organ, natural size. 



*if : 



Fig 



-Alloposus -mollis, ventral view 



oi small female, from the Pailolo Chan- 

 nel I209], X ?i Drawn by R. I,. Hud- 

 son. 



