152 PROF. OWEX ON NEW AND EAEE CEPHALOPODA. 



veins, and valvular beginnings of the two aortse'. The proportionate size of the ventricle 

 is the same which the mandibles bear to those in Onychoteuthis raptor. 



There seems no reasonable doubt, therefore, that we have in the subject of figure 6, 

 PI. XXXII. the chief part of the organs of circulation in Cook's " great hook-armed 

 Cuttle-fish." The muscular part of this heart is thickest at its widest part, near the entry 

 of the branchial veins, a, a, and gradually thins off to the fore and hind ends where the 

 aortse, h, V , are sent off. The fasciculi of fibres are disposed in different planes, and decus- 

 sate each other obliquely. The terminal aperture of each branchial vein is provided 

 with a pair of semilunar valves, c. The origin of each aorta is guarded by two similar 

 but smaller valves. The right branchial vein terminates on a plane anterior to the left, 

 and slightly affects the regularity of the lozenge-shape of the heart. 



I have reserved the most obvious and certain- evidences of the genus and present rare 

 and huge species to close such account of Enoploteuthis cookii as can now be con- 

 tributed to the Cephalopodal chapter of Zoology. 



Fortunately part of one of the ordinary eight arms (PI. XXXII. fig. 1) was rescued 

 from the cooking-galley of the ' Endeavour,' and, with the few viscera above described, 

 was put into spirits for the anatomist at home. A section has been taken, probably by 

 Hunter, from the base of the portion transmitted. The circumference of this section 

 (ib. fig. 3) is 4^ inches. The transverse section fig. 2 gives the form and diameters 

 of the present truncate end of the portion of arm fig. 1. The arm is somewhat 

 compressed, ovate, narrowest where it supports the uncinate acetabula, a, a. Its sub- 

 stance is mainly muscular. The integument is smooth and thin ; there is no trace of 

 ridge, duplicature, or production at either the line of the dorsal or of the acetabular 

 surfaces, such as are seen in the vela of Ommastrephes ensifer. Both sections show the 

 subcentral cavity, b, for lodging the bloodvessels and a nerve ; a much smaller cavity, c, 

 near the interspace of the acetabula appeared to lodge a nerve only. The muscular 

 fibres are mainly in two groups ; the mass of the external longitudinal ones, d, is, in 

 section, thickest at the acetabuliferous part, and gradually decreases to tlie opposite and 

 larger end of the section. The transverse or radiating fibres, e, pass from the thin aponeu- 

 rotic line,y', dividing their mass from that of the longitudinal ones, d, to the stronger 

 aponeurotic wall, g, of the subcentral nervo-vascular canal ; the fibres of a Avell-marked 

 fasciculus, g, act more especially upon the acetabuliferous part of the arm, tending to 

 retract it, and to strengthen or support the hooks when these are infixed in a prey and 

 when they are acted upon by the flexor and other muscular fascicles working the move- 

 ments and applications of the entire arm. The central two thirds of the general mus- 

 cular mass is condensed, seemingly by a greater admixture of tendino-fibrous tissue than 

 in the peripheral third: it suggests the idea of a flexible supporting or skeletal part of 

 the arm. 



' This was tho ground of my determination of no. 903, in the ' Catalogue' above quoted, p. 84. 



