1 19 



Fig. 45, PI. VII. Fig. 39); the blade is very narrow, compressed in the lower part, 

 widened in the outer part; the edge is irregularly sinuate, in the widened outer 

 part finely serrate. The ophicephalous pedicellariæ are rather elongate, narrow, 

 like those of Psainmecbinus rufus (PI. VII. Fig. 43); the triphyllous ones widened in 

 the outer part (PI. VII. Fig. 54) and differing in form from those of darnleyensis (which 

 are like those figured of G. pulchellus). No spicules have been found in pedicellariæ 

 or tubefeet. The spines are short, about Vs of the diameter of lest, almost equally 

 long over the whole test; the primary ones are smooth, the secondary faintly thorny, 

 as is the case in all the Gymnec/iinüs-species, and a little swollen at the point'); the 

 actinal spines are not curved. — The colour of the test is brownish, with a darker 

 median band in each area, in which the sutures may appear as white lines. The 

 spines are of a bluish or reddish tint, lighter towards the point; in the smaller 

 specimen those on the actinal side are indistinctly banded. — In both specimens 

 the genital openings are distinct. 



The 5 species of Gymnechiniis thus far known form two distinct groups: 

 the Robillardi-groui), with excentric anal area, and the darnleyensis-group, with the 

 anal area central. Perhaps these two groups ought to be made two subgenera; 

 this, however, is of very little importance. To facilitate the determination of the 

 species of Gymnechinus, which, together with Psammechinus, will doubtless prove 

 to contain yet several species, I give here an analytical table of the species. 



Table of the Gymnechinus-speeies. 



1 . Anal area central 2. 



— — excentric 3. 



2. Elongate calcareous bodies in the inner edge of the 

 buccal membrane; numerous dumbbell-shaped spicules 

 in the globiferous pedicellariæ. Valves of tridentate 

 pedicellariæ wide, not compressed in the lower part of 



the blade. Spines not swollen at the point G. ihtrnleyensis (Woods). 



No elongate bodies in the inner edge of the buccal 

 membrane; no spicules in the pedicellariæ. Tridentate 

 pedicellariæ compressed in the lower part of the blade. 

 Spines a little swollen at the point G. inconspicuus Mfîsn. 



3. Spines white G. Robillardi (de Loriol). 



— red, white tipped, not banded G. pulchellus Mrtsn. 



— banded with red, the lower part mostly green.. G. versicolor Mrtsn. 



') In ihtrnleyensis they are more evenly rounded or tapering. 



