in the Cephalopoda. 87 



distinctly, and with a slightly developed horny ring ; from this 

 point papillae, which are very low, but tolerably thick at the 

 root, follow to the apex. 



In the above-mentioned six species no striking difference ex- 

 ists between the left and right ventral arms below that part of 

 the arm which has entered into this remarkable mctamor})hosis; 

 but in Loligo media , Linn., which is destitute of acetabula on the 

 oral lobes [Mundjligene), and which has therefore been raised by 

 Gray to the rank of a distinct genus under the scarcely admis- 

 sible name of Teuthis"^, this is, on the contrary, the case (fig.l); 

 the left arm below this part, which in other respects does not 

 differ remarkably from that described in L. Forbesii and L. vul- 

 garis, being completely armed with very small suckers, whilst the 

 right arm bears large ones. The external sexual distinction 

 between males and females is consequently even greater here 

 than in any of the other species, and we may therefore the more 

 easily settle the dispute between D'Orbigny and Verany with 

 regard to the relation of this species to the L. MarmonB esta- 

 blished by the last-mentioned writer. Both in his great work 

 on the Cephalopoda, published in conjunction with Ferussac, 

 and in his ' Mollusques vivants et fossiles,^ D^Orbigny asserts 

 that the females of our species are the short-finned forms which 

 Verany has called L. Marmora, and the males, on the other 

 hand, the long-finned forms named L. subulata by Lamarck; 

 but this assertion is proved to be quite incorrect by the above- 

 mentioned sexual distinctions, as males and females occur of both 

 these forms, and of all intermediate steps between them. Con- 

 sequently, I cannot give my adhesion to D'Orbigny's opinion ; 

 but neither can I, with Verany, regard these two forms as di- 

 stinct species, as, in a series of thirteen individuals, I not only 

 find all the intermediate forms, but also a determinate propor- 

 tion between the prolongation of the abdomen and the fins and 

 the entire bulk of the animal ; for which reason 1 cannot but 

 incline to regard these external differences of form as indications 

 of a more or less complete growth, and therefore the above- 

 mentioned species as forms differing in age. 



As the seven species above mentioned represent the genus 

 Loligo, not only in all its essential forms, but also in all its 

 different ranges of distribution, I do not think that it can be 

 regarded as an unfounded assumption, that the fourth left arm 

 (ventral arm) will be found metamorphosed in a similar way, 



* Gray and Adams, who adduce Aristotle as the authority for the genus 

 {loc. cit.), must certainly have forgotten, both that it is difficult, and one 

 might almost say, impossible, at this moment to decide what Aristotle 

 meant by his Teuthis, and also that Linnaius has long since applied the 

 generic name of Teuthis to a fish. 



