30-4 THE VOYAGE OE H.M.S. CHALLENGER. 



aboral blood ring ; the stomach sphincter (da) pierced by a ring canal ; 

 inter-jaw muscle (cm) ; second mouth tentacle (r"), above which is the 

 first, marked (/) on the opposite side; irregular teeth or tooth papillae (d') ; 

 jaw plate (e) ; tentacle scales of the mouth (q) ; lower inter-arm bone 

 muscle (w) ; lower arm canal (t) ; upper arm canal (t') ; water tubes to the 

 tentacles (rt) ; upper arm plate (j). 

 Fig. 2. Gorgonocephalus poiirtalesii, Lym., f. Vertical cross-cut through part of the 



disk of a $ : digestive cavity (St) with 

 its radiating arm lobes (St'), and upper 

 lobes (St") ; the ovaries (<^), with which 

 the disk is festooned, and of which 

 many are attached to the radiating 

 lobes of the digestive cavity ; stomach 

 sphincter (da) ; (<$f), partial ring 

 canal made by a ligament attaching 

 the floor of the digestive cavity to the 

 upper part of the mouth frames (f) ; 

 first and second mouth tentacles (>•',/'); 

 papillae of mouth (d). 

 ,, 3. ,, ,, -}. Horizontal cross-cut through a portion of 



the disk, just above the arms, passing- 

 through the radial shields (I), the 

 ovarial lobes (§), and radiating lobes 

 of the digestive cavity (St"), and ex- 

 posing the digestive cavity (St) and its 

 sphincter (du) ; genital opening (no). 

 A section, inclined from the vertical, to 

 show the interior of one brachial and 

 two interbracbial spaces, above the 

 mouth, looking from the centre out- 

 ward. The digestive cavity is cut 

 through on its floor (St) just at the 

 sphincter ; and again above where it 

 passes into the thin lobes (St', St"), 

 which below are strongly attached to 

 the outer angle of the mouth frames. 

 (Am) upper surface of an arm with a 

 lobe of the digestive cavity (St 1 ) 

 attached to it. 



r 



