PEOF. OWEN ON NEW AND EAEE CEPHALOPODA. 151 



mandible. The apophysis is strengthened on each side by a broad ridge or rising, g, 

 extending longitudinally to the terminal apex. 



The muscular masses inserted into the mandibular apophyses are of a very dense 

 tissue. The hinder fascicles open, the fore ones close, the beak. The outer and inner 

 plates of the lower uncus recede in a less degree than those of the upper one ; both 

 are occupied by the condensed or tendinous modification of the mandibular muscular 

 mass. 



A thick fleshy inner lip, fig. 2, A, of a circular or sphincteric shape, immediately sur- 

 rounds or invests the mandibles : it is refiected from the base of the rostral part of the 

 upper mandible at a greater distance (about double) than from that of the lo^Yer mandible 

 (as shown in the section fig. 1, PL XXXI). The free anterior border of this lip is coarsely 

 notched or divided into lobes, answering to the finer and more numerous marginal plicae 

 present there in most of the smaller forms of Dibranchiates. The outer lip is attached 

 by eight fraena radiating from the outer side of the inner lip to the bases of the eight 

 ordinary arms. Each frsenum sends off" from the middle of its free margin a process 

 which is fimbriate (PI. XXXI. fig. 1, i, ^), but does not develop any suckers. 



The lingual apparatus consists of the tongue proper and the rasp or "radule;" to 

 which are added a pair of " faucial folds " bearing on their inner surface small but 

 distinctly visible horny denticles. The tongue proper (ib. fig. 1,^) is partially divided 

 into two lobes, into the contracted base of which is inserted a slender " retractor 

 linguEs " muscle, /. The " radule," Jc, encasing the third lobe of the lingual apparatus 

 with its horny plate, bears on the upper and fore part thereof seven longitudinal rows 

 of fine recurved spines. The faucial folds, I, I, are continued from the sides of the base 

 of the radular lobe and from the covering of the lingual salivary glands, m, as far back 

 as the beginning of the oesophagus, n. Each fold is 2^ inches in length, and 7 lines in 

 breadth at the dentigerous part, behind which they gradually narrow to their oesopha- 

 geal termination. The horny armature is on the inner surface of the broader anterior 

 portions of the folds; the spinules are slightly recurved, and afi'ect, though less regularly 

 than on the radule, a longitudinal disposition. 



The lingual salivary glands are compressed, parial, in close contact. Their vertical 

 extent is about one third of their length. They are convex and thick posteriorly, m, 

 becoming flattened and contracting as they advance to send off each their duct, which 

 opens into the cleft between the faucial fold and radule (as indicated by the bristles). 



The oesophagus, n, has a thick muscular and longitudinally plicate epithelial tunic ; 

 the diameter of the contracted tube is half an inch\ 



The systemic ventricle (Prep. no. 963, Hunterian Physiological Series; PL XXXII. 

 fig. 6) presents the same rhomboidal figure is in OnychoteutMs raptor (PL XXIX. 

 fig. 4, g), with a similar relative position of the valvular terminations of the branchial 



' A reduced out of the subject of fig. 1 is given (fig. 225), and a general notice -without details, in p. 621 of 

 my ' Lectures on the Comparative Anatomy and Physiology of the Invertebrate Animals,' 8vo, 1855. 



