BATHYPELAGIC SQUID BATHYTEUTHIS 45 



The dorsal member of the funnel or^an is an inverted Y-shaped 

 structure (pi. 7e). The posterolateral limbs are long, narrow, and 

 rounded ; the anterior limb is short, broad, and blunt. A long, flattened 

 papilla protrudes from the apex of the anterior limb. The lateral 

 borders of the organ are slightly concave, while the medial borders 

 form a curved, open V. The ventral members are elongate, oval patches. 

 The funnel valve consists of a free, semicircular flap anteriorly and a 

 muscular base posteriorly that forms a flat, deep pocket against the 

 dorsal wall of the funnel. 



The head is short and broad ; it is rounded and swollen laterally by 

 the huge, bulbous eyes that are directed anterolaterally. The eyes con- 

 stitute a very large proportion of the head. Anterior to the eye open- 

 ings the head narrows abruptly where the base of the brachial crown 

 originates. The head appears longer than it actually is because the 

 web that interconnects the arms is continuous with the integument of 

 the head. The eye openings are circular ; an optic sinus is lacking. The 

 olfactory papillae are minute projections located on the posterolateral 

 curvature of the head. The dorsal and ventral surfaces of the head are 

 flattened across the median areas, but they curve laterally. Nuchal 

 folds or crests are lacking. 



The nuchal component of the nuchal-mantle locking apparatus is 

 long and narrow with rounded ends (pi. 7d). It is bordered by a thin, 

 narrow, membranous skirt. A distinct cartilaginous ridge lies in the 

 midline; a narrow deep sulcus lies along each side. These features con- 

 form to the cartilaginous mantle component that has a deep median 

 sulcus with a high ridge on each side; this is formed by the anterior 

 end of the rhachis of the gladius. 



A small, flat, ovoid photophore is located near the base of each of 

 the dorsal six arms (pis. 6a; 10a). The light organs are embedded in 

 the integument and, as in B. dbyssicola^ are more difficult to detect in 

 large, darkly pigmented specimens. The simple organs consist of a 

 white or cream-colored central area encircled by a darkly pigmented 

 ring that is broadest posteriorly. In young specimens the photophores 

 are readily visible as raised, light or pearly organs (pi. 10a) ; the pig- 

 mented ring is much less pronounced than in larger forms. 



The arms are relatively short and conical; the tips are i)ointed but 

 not attenuate. The ventral three pairs of arms are subequal in length ; 

 the dorsal arms are always the shortest. The most frequent ann formula 

 is 4.3=2.1 followed by 4=3 = 2.1. 



A deep web joins the four pairs of arms; it extends out about one- 

 third the length of the arms (pis. 8a; 10b, d), except between the 

 ventral arms where no web occurs. The w^eb is a continuation of the 

 integument of the head and arms, so it is relatively thick and fleshy. 



