Bd. VI: 4) THE ECHINOIDEA. 69 



several distinct groups or subgenera, viz. 1) the forms with high test, posterior apical 

 system, 2 genital pores and the globiferous pedicellaria; with a circle of teeth round 

 the terminal opening {Schizaster s. str., with type species: catialiferus Lamk.); 

 2) the forms with low test, posterior apical system, 3 genital pores and tlie globi- 

 ferous pedicellariïe ending in a single tooth (subgenus Brisaster, with type species: 

 fragilis DCli. KOR.). A third group is probably formed by the species with 4 gen- 

 ital pores, gibberuliis Ag. and Savigiiyi 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 Tripylastcr 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 pedicellarije, which have the terminal opening 

 surrounded by four teeth. (The Br. capensis (Stl DER) 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 difterences in the pedicellariae 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 pedicellaria; of Tripylus are 

 strll unknown, but it can scarcely be doubted that it will ultimately be found to 

 agree with Abatus in the structure of these pedicellaria;, as it does in the structure 

 of the rostrate pedicellarise. 



The question of the species within the genus Abatus is very difficult to settle. 

 The pedicellariae, 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 pedicellariœ have been found only in two .species: cavernosus and elon- 

 gatus, 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 pedicellariae 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. bidens), but 1 cannot 

 give any other character for it than the pedicellariîe. In A. elongatus the globi- 

 ferous pedicellaria; 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. Agassizii (PFEFFER). Also the petals afford some 

 good distinguishing characters, though the most prominent feature, whether they 



