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



CEPHALOPODA. 



15 



covered by the mantle. The third arms are the longest. 

 The hectocotylisation implies an enlargement of all the 

 suckers on the third right aim (Bolitaena), or of the 

 distal suckers of third right arm (Eledonella). I intend 

 in another paper to discuss more fully the reasons for 

 establishing this new octopod family, comprising typical 

 deep-sea forms, taken in the deep-sea nets of the expedi- 

 tion at various localities. 



Eledonella Verrill. 



Eyes comparatively small and bullet-shaped. Optic 

 nerve strangely lengthened, arms frail, semitransparent. 



Eledonella pygmaea Verrill. 



Eledonella pygmaea, Verrill 1884, Trans. Connect. Acad., 

 Vol. II, p. 145, pi. XXXII, fig. 2. 



Stat. 45. 3000 m. w. 1 specimen. 



,, 53. 2600 — 3 specimens, including a male 

 having the fifth sucker (counting 

 from the point) of the 3rd right 

 arm enormously enlarged. The 

 sixth and seventh suckers are 

 smaller but still larger than the 

 others. 



„ 62. 3000 — 1 specimen. 



Bolitaena Steenstrup. 



Eyes elliptical, medium size. Arms coarse, non- 

 transparent in the specimen preserved. All the suckers 

 on the hectocotylised third arm grown large. 



Bolitaena diaphana Hoyle. 



Eledonella diaphana, Hoyle, Rep. Sc. Res. Challenger, 

 Vol. XVI, 1886, p. 107, pi. IX, figs. 3—6. 



Eyes elliptical, comparatively large; arms robust and 

 in preserved specimens opaque. 



Stat. 35. 2400 m. w. young specimen. 

 „ 53. 1600 — — „— 



„ 53. 2600 — two well-preserved adult speci- 

 mens. 

 ,, 56. 300 youngest specimen. 



Small and transparent young stages of Bolitaenidae 

 were taken at the following stations, but they are not 

 easily referred to definite genera: 



Stat. 64. 3000 m. w. 

 „ 92. 300 — 

 „ 92. 1500 — 



.■.♦ 



Fig. 6. Bolitaena diaphana. Nat. s. Stat. 53. 



Cirroteuthidae Keferstein. 

 Opistoteuthis Agassizii Verrill. 



Stat. 4. Trawl, 923 m. 4 specimens, which are 

 very soft and considerably damaged. On the dorsal side 

 the main colour is violet and on the ventral side chocolate 

 brown, the light coloured suckers being very conspicuous. 

 Judging from Verrill's figure (Bull. Mus. Comp. Zool. 

 Cambridge, Mass., Blake Cephalopoda, Suppl. 1883, pi. 1 

 & 2) the animal is longer in the median line than in 

 transverse section. This does not apply to our specimen 

 inasmuch as both axes are of equal length. 



In two specimens I have found an enlargement in 

 certain suckers, and I do not think I am wrong in sup- 

 posing that this is connected with hectocotylisation. The 

 largest and best preserved specimen exhibits after the 

 sixth proximal sucker 4 or 5 broadened arm-suckers, of 

 which the middle one is largest while the others decrease 

 gradually in size. At the point of the arms 2 suckers are 

 generally enlarged, sometimes abnormally so. Some of 

 these enlarged suckers exhibit pathological alterations, 

 being swollen and. devoid of an aperture. The same 

 condition is also found in smaller specimen, not only 4 

 or 5 proximal suckers but also 2 or 3 distal ones having 

 been enlarged. 



