1G6 HAWAIIAN AND OTHER PACIFIC ECHINI. 



twice as many feet as in the inner, each foot in the latter series being 

 opposite alternate feet in the former ; in the inner series, small primary 

 or large secondary tubercles alternate with the feet, so that, while the 

 outer series consists of feet only, the inner consists of alternating tuber- 

 cles (spines) and feet. In the specimens from 3784 this arrangement is 

 very evident, but it is not quite so clear as in the "Challenger " specimen, 

 because the feet are larger and nearer together vertically. In the speci- 

 mens from 4928 and 5084, it is not at all noticeable, because the tube-feet 

 are small, light colored, and rather far apart vertically. 



The pedicellariae of tenue are not very characteristic, for while they 

 show no little diversity, no one form is really distinctive. Ophicephalous 

 pedicellariae are numerous on the abactinal surface just above the ambitus 

 in one of the specimens from 4928 and in one of those from 5084 ; a few 

 were also found in the second specimen from 4928 and one in the second 

 (smaller) specimen from 5084 ; in the " Challenger " specimen and in the 

 two fine individuals from 3784 there are none. The occurrence of ophi- 

 cephalous pedicellariae seems to be, therefore, an individual and not a specific 

 character. Tridentate and triphyllous pedicellariae are abundant and more 

 or less variable. 



The triphyllous pedicellariae (PI. 67, fig. 19) have very slender stalks, with 

 the neck of variable length, usually several times as long as the head. 

 The valves (PI. 67, figs. 15, 20) are rather broad, about half as wide at 

 the tip as they are long, or a little wider ; they are usually somewhat trun- 

 cate at the tip, but those on the specimens from 3784 are often more 

 rounded (fig. 15) ; they are about half a millimeter long. 



The tridentate pedicellariae (PI. 67, figs. 12, 17) vary greatly in size and 

 more or less in form. In the larger ones the neck is short and the stalk 

 is only a little longer than the head, while in the smaller ones the neck 

 may equal the head and the stalk be several times as long. In the largest 

 the valves (PI. 67, figs 13, 16) may be 2.5 mm. long ; they are straight, 

 usually meet for their full length, and the sides of the blade are more or 

 less nearly parallel and not at all involute; the blade is more or less filled 

 with a calcareous mesh-work, and the apophysis usually extends into the 

 blade as a serrate median ridge. In the specimens from 3784 the 

 large pedicellariae are quite variable, and in many of them the valves are 

 separate at the base (see PI. 67, fig. 12) for a greater or less distance ; 

 the valves are also more or less constricted at the base of the blade and 



