156 PROF. OWEN ON NEW AND BAEB CEPUALOPODA. 



the great Squid when he applied the name " Banksii " to a small African hook-armed 

 species, which, in 1817, he deemed identical with the larger one of the Pacific Ocean. 

 M. d'Orbigny limits his notice of this truly remarkable Cephalopod to the following 

 passage : — " On ne connait de cette espece qu'une partie d'un bras sessile gigantesque, 

 convert de crochets sur toute sa longueur. Ce caractere etant celui des Enojiloteuthis, 

 je I'ai place dans ce genre. Je dois a Tobligeance de M. Richard Owen uu beau dessin 

 de ce bras depose au Musee du College des Chii-urgiens de Londres." — Oj). cit. p. 339 

 (1848). The drawing was a copy of that (PI. XXXII. fig. 1) which accompanies the 

 present paper. My esteemed correspondent and fellow-labourer made no use of it for 

 his great work. 



Cephalopods remarkable for large Size. 



Genus Plectoteuthis i, Owen. 

 Species Plectoteuthis grandis, Owen. 



It has been shown (p. 144) that the side of the arm opposite the acetabuliferous 

 tract is longitudinally and mesially ridged, and there more or less produced, in certain 

 Squids (Loliginidte) ; but in the British Museum is preserved one of the eight ordinary 

 arms of a Cephalopod which, from the characters of the cups (PI. XXXV. fig. 2), is 

 referable to the genus Ommastrephes, d'Orb., but which supports them on a relatively 

 broader flattened tract (ib. ib. «), and presents on the opposite or dorsal side (PI. XXXIV. 

 fig. 2) a similar flattened tract, a, from each margin of which a fold of the integument, 

 h, is produced, of varying breadth. A transverse section of the arm consequently gives 

 a quadrate instead of triangular form, in this respect repeating the character shown in 

 Loligopsis ocellata. 



The cups or suckers are arranged in a double alternate row along their tract, the 

 margins of which are produced into a well-defined fold or thin seam (PI. XXXV. flg. 2, 

 c, c), but of minor breadth than the dorsal folds. This plicatile condition of the 

 ordinary arms has suggested the generic name. 



The length of this arm, which has been amputated at or near its base, is not less 

 than 9 feet ; the diameter of the amputated base from within outwards is 4 inches ; 

 the same from side to side is 3 inches ; the total circumference is 1 foot. At this basal 

 part of the arm (PI. XXXV. fig. 1) the acetabula have not begun to be developed ; it 

 would seem to correspond to the non-acetabular tract extending, in most Loliginidffi, a 

 short way from the outer lip. Here, in Plectoteuthis, the folds are restricted to the 

 dorsal pair (ib. fig. 1, b, b), but they do not exceed an inch in breadth. The opposite 

 surface, a, a, is convex across : this convexity broadens into flatness as the arm extends 

 and begins to develop its cups. The circumference, taken midway between the two ends 

 of the arm, is 9 inches. The breadth of the acetabuliferous tract at 6 inches from the 

 amputated end is 5 J inches with the marginal folds outstretched ; the interspaces 



' Gr. ttXcktos, folded, revtiis, Squid. 



