Boone, Echinodermata, Cruises of "Ara" and "Alva" 175 



entire length of the spine ; the collar is also striated. The smaller 

 spines, f oraiing the fasciole, are not quite one-fifth as long as the 

 large spines and are exceedingly slender, usually pointed distally ; 

 they are also longitudinally ridged with fine asperities in series, 



Pedicellariae of three kinds were found, the elongate tri- 

 dentate type, shown in plate 67, figure b, which are moderately 

 numerous on the abactinal system, also about the peristome and 

 periproct. The interior of the valve of this tridentate pedicellaria 

 has a median septum proximally, the lateral-distal margins are 

 non-dentate except for a single beak-like apical hook or tooth, as 

 shown in figures b and c. The second type of pedicellaria, shown 

 in figure d, the large globiferous pedicellariae, which are 

 much less abundant than the other two kinds, are to be found 

 quite numerously around the peristome. These stout forms are 

 1.6 times as long as wide proximally, with the proximal half 

 within the valves filled by the gland ; each valve has the proximal 

 inner chamber divided by a median longitudinal septum ; the nar- 

 row distal portion of the valve is coarsely serrate, there being a 

 strong apical tooth, on either side of which there are two coarse 

 triangular teeth near the apical and a third distinct but smaller 

 tooth, about as far below the second tooth as the latter is from the 

 apical tooth. The inner surface of the distal portion is concave, 

 devoid of any inner aperture. The small globiferous pedicellariae, 

 which are moderately numerous, especially within the petaloid de- 

 pressions, are not quite two-thirds as large as the large globiferous 

 pedicellariae and are about 1.4 times as long as wide, broader 

 apically in ratio to their size than are the large type and with dif- 

 ferent kind of valves. These valves, shown in figure c, have the 

 wider proximal portion of the valve divided internally by a 

 median septum which is distally bifurcate; the apical portion of 

 the valve curves inward, the distal margin being wide, rounded, 

 somewhat like a broad spoon, this distal-apical margin bearing six 

 serrate teeth of moderate size. 



In one of the smaller specimens of the present series ambula- 

 crum III is so very deeply sunken and the labium narrowed and 

 projecting that the peristome approaches a vertical instead of the 

 usual horizontal position it occupies in the larger specimens of 

 this series. 



