MUSCULAR SYSTEM. 



149 



FIG. 69. 



funnel consists chiefly of two strata of muscular fibres, the 

 inner of which is transverse, and the outer longitudinal. In 

 the annexed front view of the muscles of the argonaute, 

 (Fig. 69,) the funnel (e,) is folded down over the fore part of 

 the abdomen (/,) and 

 its strong posterior 

 muscular bands (d, d,) 

 are seen passing down- 

 wards from its base. 

 The anterior ascending 

 radiating fasciculi (a,) 

 cross each other at the 

 bases of the feet, so as 

 to interlace and mingle 

 their fibres before they 

 enter into the compo- 

 sition of these organs. 

 These muscular fibres 

 are more straight and 

 parallel as they advance 

 along the feet (b 9 ) en- 

 veloping the trunks of 

 the vessels and nerves which are seen ramifying on the ex- 

 panded terminal membrane (c,) of the posterior pair of feet. 

 The suckers in two rows, as on the other feet, continue 

 around the margin of these expanded terminations of the 

 posterior pair. All the naked cephalopods are octopods, like 

 this testaceous argonaute, having only eight feet developed 

 from the muscular disk surrounding the mouth ; but many 

 of the genera, as sepia, loligo, and sepiola, have also two long 

 muscular tentacula, which have a deeper origin near the car- 

 tilaginous orbits, and from these superadded pediform tenta- 

 cula, such genera have been considered as decapods. The 

 rudimentary eye-lids of the naked cephalopods are already 

 surrounded with distinct orbicular muscles, and the eye- 

 balls are moved by four recti muscles, and sometimes by an 

 inferior oblique, arising from the base of the orbits around 

 the optic nerves. The tentacula have generally pedunculated 

 muscular suckers developed on their inferior surface, at their 

 free extremities, like those of the feet in the tentaculated 

 species of this class. The muscular suckers are sessile, large, 



