114 



are disposed in rather inclined arcs, the outer pair being placed close to the edge 

 of the area. At the peristome the pores are smaller, the pore-area narrower than 

 at and above the ambitus. The plates are rather high, not much exceeding the 

 interambulacral plates in number. The sutures are rather indistinct, somewhat 

 inclining outwards. The primary tubercles (one to each ambulacral plate as in 

 the other species of this genus) form a verj' distinct and regular vertical series, 

 diminishing a little in size towards the apical system and very little so towards 

 the peristome. Inside the primary tubercle there is a smaller secondary one at 

 the upper edge of the plate, forming likewise a more or less regular vertical series; 

 in larger specimens a secondary tubercle may be found also at the inner edge of 

 the plates at the ambitus. Between the primary tubercle and the pores there is a 

 small tubercle on each plate, forming likewise a regular vertical series. 



The interambulacral plates have a primary tubercle situated about in the 

 middle of the plate, not much larger than the ambulacral ones; they form a beautiful 

 vertical series, not distinctly diminishing in size towards the mouth or apex. Inside 

 the primary tubercle there is, as in the ambulacra, a secondary tubercle at the 

 upper edge of the plate and one at the inner edge; the latter is mostly the larger 

 and may form a rather prominent vertical series. A few more small tubercles maj' 

 be found, irregularly placed. Outside the primary tubercle some secondary tubercles 

 are found, partly disposed, in larger specimens, in two more or less distinct vertical 

 series, and forming also together with the primary tubercle and the median inner 

 tubercle a more or less distinct horizontal row of four tubercles. Miliary tubercles 

 very few and indistinct. 



The apical area is like that of G. Robillardi (de Loriol.) (PI. II Fig. 11). The 

 periproct is pushed out towards the right posterior Interradius, the corresponding 

 genital plate being quite low. The genital plates of the opposite side are on the 

 contrary very high and large; sometimes one or two of them are divided by 

 a transverse line into an inner and outer part, and sometimes one of the genital 

 plates, mo.stly the left anterior, may be excluded from the periproct. The genital 

 openings are formed already in specimens of 5 mm. diameter. The two ocular 

 plates are broadly in contact with the periproct, the others widely separated 

 therefrom. A single rather large tubercle is found in the middle of each genital 

 and ocular plate, except the posterior, low genital plate. The periproct is covered 

 by several small, irregular, smooth plates, among which no distinct central plate 

 can be made out (in larger specimens). The anal opening is situated nearest to the 

 posterior edge of the periproct. 



The buccal membrane is naked; in the oral edge a single irregular rod may 

 be found, but mostly there is none. Outside the buccal plates some very few small 

 fenestrated plates may occur in larger specimens. Bihamate spicules are almost quite 

 wanting in the buccal membrane; in the gills there are mostly a few; here and there, 

 however, larger numbers are found, bill llie usnal irregular, fenestrated plates are not 



