ECHINOIDEA. II. 



35 



The petals are considerabh' shorter and less developed than in piisi/liis. the mimber of pores 

 being almost double in the latter species, when comparing; specimens of a corresponding size of 

 the two species, as is easily seen from the table given and from a comparison of figures 5 and 31. 

 PI. XII. The pores are soniewhat smaller than in p/tsil/iis (those of tlie inner series smaller than 

 those of the outer series), with no distinct glassy protnberance between the pores of each pair; the 

 pairs are also more oblique and more distant than in pnsillns. It is fnrther a conspicnons feature 

 that the petals are converging outwards, the two series of each petal being more distant at the inner 

 end — likewise a very conspicnons difference from piisillus. (Comp. Figs. 5 and 31. PI. XII). (In one 

 specimen, 8-5""" in length, the petals are quite irregular, consisting of some few, scattered pairs of 

 pores; onl\- the right posterior petal is almost normal. Also the genital and ocular pores are qnite 

 abnormally placed in this specimen). There is fnrther a considerable difference from pitsilliis in the 

 number of the small ambnlacral pores; on the actinal side they are arranged onl\ in a .single series 

 along each horizontal suture, except in the two inner pairs of sets, in which thev form, more or less 

 distinctly, two series. This is the case also 

 in the largest specimens seen, 9""" in length. 

 On the abactinal side the\' are arranged as 

 in pusilhis, only I ha\'e been unable to dis- 

 cern witl) certainty such pores within the 

 petals. The genital pores I have found de- 

 veloped in a specimen onh- 2'8™™ in length; 

 on the other hånd I have also seen a speci- 

 men of 4™™ length with as yet no traces of 

 genital openings. Large genital papilke ina\' 

 be developed. 



The tuberculation is soniewhat less 

 close than in piisillus. and tlie glassy protube- 



rances among the tubercles are likewise less numerous, but, on the other hånd, they are more promi- 

 nent being considerably higher than the primary tubercles; they are striated, ending in a knob, almo.st 

 like the mamelon of a tubercle, which is, however, not perforated, since no spine is articulated to it. 

 (PI. XII. Fig. 14.) This seenis, however, to be a rather inconstant feature, and in any case it is very 

 indistinct in less well preserved specimens. 



The supportiug ridges of the interior of the test (PI. XII. Fig. 3) are less strongly developed 

 than in pusillus, not proceeding to the auricles as in the latter species, but ending some way out- 

 .side the auricles, which are also more distant from the edge of the peristome than in pusilbis. (Comp. 

 PI. XII. Fig. 3 and 29.) It will be seen that the figure given in Revision of Echini PI. XIII. 7 is 

 much more in accordance with the figure given liere of grandiponis tlian with that of piisillus. though 

 not quite agreeing with this figure either. The depressions along the ambnlacral sutures are much 

 less prominent than in piisillus. — In accordance with the place of the auricles the dental apparatus 

 is considerabl}' larger than in pusillus, as sliown in Fig. 2, which represents the dental apparatus of 

 specimens of 7'"'" length of pusillus and grandiporus. Botli agree in having it unequalh" developed 



5* 



Fig. 2. Dental apparatus of Echinocyamus. ym" 

 a Ech. grandiporus. i Ech. pusilhis. '/"/i. 



