84 Prof. J. Steenstrup on Hectocotylus-/or»z«/jon 



of pairs of acetabula have been metamorphosed ; they diminish in 

 length in both rows towards the apex, but those which are placed 

 along the outer margin of the arm are at the commencement more 

 elongated in proportion, whilst the subsequent ones, in a certain 

 space of the metamorphosed part of the arm, are abbreviated, 

 and seated on its margin like small serrations [vide PI. II. 

 fig. 2*). 



* The specific distinctions between Lo%o vulgaris, Lamk., and LoUgo 

 Forbesii, Stp., are best derived from the size and form of the suckers on 

 the tentacles : in L. vulgaris of the Mediterranean, as described and figured 

 bv D'Orbigny and Yerany, and also in a form of our coasts, which may 

 certainly be regarded as L. vulgaris, these are veiy large in the two central 

 rows, and very small in the lateral rows, so that a transverse section of the 

 latter is onlv one-half of that of the former, and their height only one- 

 third; whilst in L. Forbesii, Stp., the suckers of the central rows scarcely 

 exceed those of the lateral rows, either in transverse section or in height ; 

 and, on the whole, it appears as if the club of the tentacle had four series 

 of suckers of equal size. In comparison with the suckers of the arms, the 

 disks of the central rows of the tentacles in Loligo vulgaris are 2-3 times 

 as large a«the largest disks on the third aim, whilst in L. Forbesii they are 

 scarcely one-third larger. The horny ring in the central rows of suckers 

 in L. vulgaris has only one-half of its circumference finely toothed, whilst 

 the other half is toothless, or only bears a group of 4 5 small blunt teeth 

 (in our northern form these are indeed the only teeth on the homy ring) : 

 in Loligo Forbesii the ring bears numerous pointed teeth all round, and 

 these are usually larger and smaller alternately. In this species, also, the 

 suckers of the lateral series have the horny ring completely set with teeth 

 of equal size, whilst in L. vulgaris their horny ring has high pointed teeth 

 in the upper half, and the lower half almost toothless. In colour also, 

 L. Forbesii is characterized by having the colour-sacs united into linear 

 s])ots on the anterior part of the sides, and also down the ventral surface. 

 These long, dark markings, and the nearly uniform size of the tentacular 

 suckers, consequently distinguish this species from L. vulgaris at the first 

 glance. Of both species I have only been able to examine the males on 

 our coasts ; with us, L. Forbesii is the largest and most common. The 

 ordinarj' specimens are at least 2 feet long with the tentacles, 20 inches to 

 the tips of the arms, 15 inches to the roots of the arms, and the mantle = 

 1 foot. 



The figures which certainly represent L. Forbesii are — r 



Forbes and Ilanley, British MoUusca, vol. i. pi. L.L.L. 



Adams (H. and A.), The Genera of Recent Mollusca, pi. 4. fig. 3 : 



in the former place under the name of L. vulgaris, Lamk. ; in the latter, 

 under that of L. magna, Rondel. 



It is also this species that I have figured in a woodcut in mv memoir 

 upon the " Sea-monk" (Somunken) ; and, to judge from the suckers, it is 

 also possibly the species represented by Borlase (Natural Histor}' of Corn- 

 wall). 



As Rondelet's name " Loligo magna" is no systematic denomination in 

 the Linnfean sense, this name, adopted by Leach, Gray, and others, cannot 

 be justly regarded as prior to L. vulgaris, even if it cannot be abandoned 

 for the reason adduced by D'Orbigny, because there are other large spe- 

 cies ; but least of all can this name be transferred to the new species, which, 

 in the opinion of the malacologists of Southern Europe, is an Atlantic spe- 



