CEPHALOPODA OF THE HAWAIIAN ISLANDS. 327 



of the arm , but regularly diminishing to the tip ; (2) the two dorsalmost rows continue down the club prox- 

 imally for its entire length, attaining their maximum dimensions near the middle; the two ventral rows 

 on the other hand abruptly cease and are replaced on the proximal half of the club by (3) a single series 

 of five rather large hooks which stand opposite the five proximal pairs of suckers in the dorsal rows; 

 (4) at the base of the club, upon the carpus, is a very definite fixing apparatus comprising a double row 

 of some four to five suckers alternating with a similar number of small whitish pads. (PI. LI, fig. 2, 6.) 



Buccal membrane eight-pointed (as correctly surmised by Pfeffer, my original assertion that there 

 are but seven lappets is erroneous); coarsely papillose within. 



Photophores of the outer integument exceedingly numerous and readily perceivable to be in two 

 main sizes, the grouping of the larger of which is distinctly bilaterally symmetrical and varies on different 

 regions of the body as follows: 



(1) On the ventral aspect of the mantle appear about ten rather ill-defined longitudinal series of 

 these organs, including (a) two nearly median rows of relatively large organs extending without inter- 

 ruption from the anterior mantle margin to the posterior extremity; (ft) two similar series succeeded 

 laterally by two or three others, composed of organs constantly diminishing both in size and number, 

 occur parallel to these anteriorly, but all converge posteriorly in such a way that in addition to the two 

 central series but one other row persists on each side to the tip. The organs of the various series are 

 very regularly and equally interspaced so that there is a certain tendency evident for the grouping to 

 occur in a transverse as well as a longitudinal direction. Aside from the effect which might well be 

 expected to result from such a tendency, no specially definite line of photophores is found bordering 

 the margin of the pallial aperture. The smaller organs are much more numerous than the larger and 

 occur scattered between and among them in a much more irregular fashion. On the dorsal surface of 

 the mantle photogenic organs are almost entirely wanting, but there is a fairly regular series of about 

 seven small distant organs close to the median longitudinal line on either side, and some distance lateral 

 to these a few (3 to 4) isolated organs, perhaps representing the rudiments or forerunners of other longi- 

 tudinal series. 



(2) The ventral aspect of the funnel exhibits a little in front of its middle a transverse line of four 

 large organs of equal size, in front of and behind which occur a number of smaller ones in such a way as 

 to form four longitudinal series containing one of the large organs and two to three of the smaller ones 

 e;ich. A few scattered organs occur in addition, but all are bilaterally arranged. A clear space down 

 the center of the funnel separates the photophores of each side into two triangular patches. This space, 

 like the extreme tip of the funnel, is colorless and devoid of organs. 



(3) There are no photophores upon the upper surface of the head, but upon the lower aspect they 

 appear with perfect symmetry in five longitudinal rows with an additional series bordering each ocular 

 aperture. Here also the larger organs are relatively few in number compared with the smaller, there 

 being only two of the former in the median row, and two to three in each of the lateral series. The 

 median row bifurcates at the apex of the funnel groove (one large organ on either side), and also anteri- 

 orly, where either branch parallels a continuation of the first lateral series along each ventral arm to its 

 extremity. The outer lateral series continues for a distance along the border of the membranous keel, 

 so that the basal half of each ventral arm bears in all three rows of photophores. The arms of the third 

 pair have a series of these organs near the base along their ventral aspect, and there are evidences of a 

 second row of smaller ones along the dorsal margin as well. No such structures have been identified 

 upon any of the other arms or upon the tentacles. 



All of the photophores appear as minute, but definite, faintly elevated, circular, bluish rings, 

 surrounding a white dotlike center, and having much the appearance of minute eyes. The bluish 

 rings are relatively heavier and more conspicuous in the larger organs, while the smaller organs are by 

 this means again separable into two types, the one much less heavily pigmented than the other. 



In addition to photogenic organs of the general type described above, there are to be observed a 

 very conspicuous series of five large reddish bead-like structures upon the ventral periphery of each 

 eyeball. They are placed very close together, are of circular outline and subequal in size (pi. LI, fig. 3). 

 The two terminal organs are considerably lighter in color than the three median ones. 



