CEPHALOPODA OF THE HAWAIIAN ISLANDS. 



279 



Fig. 5. — Argonauta bottgeri, out- 

 line drawing of funnel laid 

 open medioveutrally to show 

 the funnel organ [165], X 2. 



modified extremities of the dorsal pair, on which latter only the basal 15 to 16 are at all well developed. 

 The funnel is connected to the head dorso-Iaterally by a pair of delicate bridle-like connective mem- 

 branes, which are continuous with a delicate keel running along the lower aspect of each ventral arm; 

 otherwise the arms are rounded and devoid of keels or swimming membranes. Dorso-laterally the 

 integument of the head is connected with the dorsal arms by a delicate 

 vertical membrane bridging the sulcus which otherwise separates the arms 

 and head, and two similar but smaller membranes bridge the constriction 

 between the anterior boundary of the eyeball and the lateral arms. 



Shell small for the genus, coiled very compactly in an even plane, 

 laterally compressed ; the sides ornamented with some 30 or more conspicu- 

 ous ridges radiating from the shallow depression which is the outward 

 mark of the shell axis; periphery flattened, each angle decorated with a 

 row of bluntly squared tubercles, 17 to iS of which can be made out on 

 each side; margin of aperture simple, without any trace of lateral expan- 

 sions or " auricles; " surface finely and quite evenly granulose, the granules 

 most numerous on either side of the shell near the axis and visible without 

 the aid of a lens (fig. 4) . 



General surface color of animal in alcohol everywhere a pale brown- 

 ish buff, dotted more or less impartially with numerous fairly large bluish black chromatophores, 



which are nowhere crowded save on the outer aspect of the dorsal 

 arms and in less degree the dorsal integument of the eyeball. 

 Beak coal black. 



As no male animal of this species has come to hand the above 

 description applies only to the female. However, the mantle of 

 the specimen before me was carefully laid open along the medio- 

 ventral line ; lying within the cavity, its thickened basal portion 

 lodged snugly just above the left gill between the latter organ 

 and the viscera, was found the detached hectocotylus of a male. 

 This condition is well shown in the accompanying sketch, which 

 indicates the position of the structures in question in situ (text 

 fig. 6); see also the more detailed representation of the hecto- 

 cotylus in figure 7. The organ comprises a thickened basal por- 

 tion curved in the shape of a horseshoe about 6 mm. in length by 

 a little more than 4 in breadth, with the inner or sucker bear- 

 ing aspect outermost; widest between the middle and the base, 

 tapering slightly to a rounded point posteriorly, and more gradu- 

 ally to the acute distal extremity which terminates in a very long 

 and slender thread-like process, lying in a loose coil ; the basal 

 portion broadly flattened on its inner surface, the margin of the 

 latter armed with a closely placed row of minute much elevated 

 suckers, about 22 on each border, which are connected by a deli- 

 cate hyaline membrane; the outer aspect (i. e., inner curve of 

 the horseshoe) is keeled and bears a conspicuous marginal mem- 

 brane, which even continues along the terminal thread, though 

 there becoming extremely thin and delicate. The diameter of the basal portion is 2 mm. ; the length 

 of the flagellum about 13 mm. 



The shell of this specimen was partly full of eggs and young embryos connected into a loose mass 

 by fine filaments and representing various early stages of development. The total number is several 

 hundred at least, the largest scarcely a millimeter in length. 



Fig. 6. — Argonauta bottgeri [165], ventral 

 aspect of female, with mantle laid pal* 

 tially open to show the detached hecto- 

 cotylus of the male in situ within the 

 paUial chamber, X 2: br., gill; hect., hec- 

 tocotylus of male; 1. app., locking carti- 

 lages of left side; mb., thickened band 

 of muscular tissue bordering mantle mar- 

 gin; ov., gonad; sept., median septum of 

 pallial chamber. 



