Bd. VI: 4) 
THE ECHINOIDEA. 
6 9 
several distinct groups or subgenera, viz. i) the forms with high test, posterior apical 
system, 2 genital pores and the globiferous pedicellariæ with a circle of teeth round 
the terminal opening ( Schisaster s. str., with type species: canaliferus Lamk.); 
2) the forms with low test, posterior apical system, 3 genital pores and the globi- 
ferous pedicellariæ ending in a single tooth (subgenus Brisaster , with type species: 
fragilis DüB. Kor.). A third group is probably formed by the species with 4 gen- 
ital pores, gibberulus Ag. and Savignyi FoURTAU, for which the name Paraster 
POMEL should be used, and finally a fourth group is formed by the species Philippii 
Gray, for which the name Tripylaster is proposed. The characters by which this latter 
group is distinguished from Brisaster are: the subcentral position of the apical system 
and the structure of the globiferous pedicellariæ, which have the terminal opening 
surrounded by four teeth. (The Br. capensis (Studer) is, however, very similar to 
Philippii as regards the shape of the test.) To Abatus this species bears several 
resemblances, but the distinct latero-anal fasciole, the not deepened petals, besides 
some minor differences in the pedicellariæ separate it clearly from that genus. It 
may well be said to stand between Abatus and Brisaster , but the affinities seem to 
be more close to the latter. From the genus Tripylus it differs markedly in the 
structure of the petals; unfortunately the globiferous pedicellariæ of Tripylus are 
still unknown, but it can scarcely be doubted that it will ultimately be found to 
agree with Abatus in the structure of these pedicellariæ, as it does in the structure 
of the rostrate pedicellariæ. 
The question of the species within the genus Abatus is very difficult to settle. 
The pedicellariæ, which are in so many cases of very great importance for dis- 
criminating the species, are only of small use in this regard in the present group. 
Globiferous pedicellariæ have been found only in two species: cavernosus and elon- 
gattis, and in the former, moreover, they occur in two very distinct types with 2 — 3 
teeth on either side of the terminal opening or with only one tooth on either side (PI. 
XIX Figs. 28, 29, 33 to compare with fig. 32 and 39); one would rather think them to 
form a generic than a specific distinction — but the specimens with these two different 
forms of globiferous pedicellariæ are so much like each other that — judging from the 
material in hand — it seems impossible to distinguish them by any other character. I 
think it correct to note this form as a variety of cavernosus (var. b idens), but I cannot 
give any other character for it than the pedicellariæ. In A. elongatus the globi- 
ferous pedicellariæ have only one tooth on either side of the opening. — The tube- 
feet afford one character of importance for distinguishing the species, viz. in the 
subanal tubefeet; these may be penicillate in the usual way, or they may be quite 
rudimentary, not penicillate. The latter case obtains in A. cordatus and in one of 
the South American species, A. Agassisii (PFEFFER). Also the petals afford some 
good distinguishing characters, though the most prominent feature, whether they 
