of British Mollusca. 467 



organ, of which the inner concave side is transversely divided 

 by a number (thirteen in my specimen) of ribs which slightly 

 incline forwards; anterior to these there is at the base a 

 V-shaped fold, the point of the fold being directed forwards. 



The largest Irish specimen has a total dorsal length from 

 the extremity of the body to the end of a dorsal arm of 161 

 millim.; of this the body and head occupy 47 millim., the 

 membrane connecting the arms 40 millim., and the free por- 

 tion of the arm 74 millim. ; breadth of body 45 millim. The 

 animal was preserved in strong spirit. 



" Lamellse radulse medianae basi semielliptica, tnargine 

 antico leviter emarginato, postice convexo, acie acuminata, 

 marginibus Iambus, non denticulatis. Segmenta radulse 64." 

 (G. 0. Sars.) 



Mr. G. C. Bourne trawled two fine females of this species 

 last year in H.M.S. ' Research ' off the south of Ireland. 

 The smaller specimen is not so tuberculate as the larger, 

 and neither of them shows the more elevated supraorbital 

 process, though that portion of the animal is more covered 

 with prominent tubercles than the rest of the body. In 

 this respect it accords with an American male for which I 

 am indebted to the United States National Museum. Mr. 

 Hoyle has also examined the specimens, and agrees with me 

 that they belong to this species. I have also to thank that 

 friend for information on several points on which [ have con- 

 sulted him in reference to the Cephalopoda. 



Distribution. Octopus arcticus occurs off the whole north- 

 east American coast from Newfoundland and Nova Scotia to 

 South Carolina in 45-524 fathoms. G. O. Sars has found it 

 off* West Norway, Lofoten, and East Finmark in 80-300 

 fathoms. In the ' Porcupine ' expedition it was twice met 

 with in the Faroe Channel in 345-632 fathoms, and in the 

 same Channel it was procured by the ' Knight Errant ' in 

 540 fathoms, and by the ' Triton ' in 608 fathoms ; and if it 

 be Sepia grcenlandica, Dewhurst, it also lives in the Green- 

 land Sea. 



Fam. 2. Eledonid.se. 



Genus 2. Eledone, Leach. 



Radula having the central tooth very large and acute. 

 With two teeth on each margin towards the base ; two laterals 

 on each side, the inner small and rudimentary, the outer 

 unicuspidate and large (but much smaller than the great 

 central tooth) ; a single falcate uncinus on each side curving 



33* 



