Bd VI: 4) THE ECHINOIDEA. 87 



pedicellarise occur. — Otherwise I have nothing to add to the description given by 

 AGASSIZ (Op. cit., under the name of Hemiastcr australis and cavernosus). 



The pedicellariae do not afford very useful characters. Globiferous pedicellariae 

 I have not found, except in a fragment from South Georgia labelled H. Agassizii 

 by Prof. PFEEFER; its somewhat deepened frontal ambulacrum and shorter posterior 

 petals, however, make it very probable that it is not this species but cavernosus; 

 the globiferous pedicellariae end in two teeth, which would seem to show that it be- 

 longs to the var. bidens. (The posterior end of the test is not preserved so that it 

 could not be seen whether the subanal tubefeet have been developed or not.) In 

 case the H. elongatus is really a synonym of this species, the globiferous pedicella- 

 riae are provided with two teeth as in cavernosus var. bidens. The rostrate pedi- 

 cellariae are of the usual form; the tridentate pedicellariae, on the other hand, differ 

 from those of the other species in having, viz. the larger ones, a well developed, 

 spinulose meshwork or crests in the blade (PI. XIX. Fig. 40). Also the shape of 

 these larger pedicellariae is somewhat different from what is found in the other spe- 

 cies, the outer widened part being relatively larger. The smaller forms are as in 

 the other species. — The spicules do not differ from those of the other species; 

 this also holds good of the colour. 



A young specimen (from South Georgia) of 12 mm. length (PI. X. Figs. 1, 3) 

 shows already all the characters of the species typically developed, being very dif- 

 ferent from specimens of cavernosus of a corresponding size (cf. PI. IX. Figs. 7, 9). 

 This decidedly points towards the specific distinctness of the present form. Even a 

 specimen of 6 mm. length (likewise from South Georgia) looks rather different from 

 cavernosus of a corresponding size — though it may, upon the whole, scarcely be 

 possible to distinguish with certainty very young specimens of the different species 

 of Abatus. 



This species was taken by the Swedish South Polar Expedition at Station 19 

 (54T4' S. 30*31' W. 10 — 15 m. South Georgia), 5 specimens, and Station 33 (54°22' S. 

 36°28' W. 22 m. South Georgia), 1 specimen. The specimens from the Hamburg 

 Museum likewise came from South Georgia. From the ^Revision of Echini» it 

 may be concluded that it occurs also at the Patagonian (and Chilian?) coast. It 

 appears to be a strictly littoral species. — The A. elongatus was found at the 

 South Orkneys. 



Tripylus excavatus Phil. 



PI. XI, Figs. 1, 14, 16. PI. XII, Figs. 2, 4, 6, 9. PI. XIX, Figs. iS, 34, 44. 



Tripylus excavatus Philippi. 1845. Beschreibung einiger neuen Echinodermen. Arch. f. Naturgesch. I. 

 p. 344. Taf. XI, Fig. 1. 

 — A. Agassiz. 1872. Revision of Echini, p. 169, 588. PI. XXI. c, Fig. 4. 

 — — — 1874. >Hassler» Echinoidea, p. 22. 



