HEMIASTERIDAE 227 



biilacruni, behind the fascicle. They are very conspicuous on account of their dark 

 colour, the general colour of the specimen being a light brownish. In the smaller 

 specimen they are not nearly so numerous and are much less conspicuous, due to the 

 specimen having been dried. The valves (Plate IX, figs. 19, 20) are small, elegantly 

 curved (the species name curvidens refers to this feature), terminating in two or three 

 long slender teeth ; the number of the teeth appears to be more generally two, but it is 

 by no means rare to find three of them. Often there is an irregular hump on the dorsal 

 side of the valves. The rostrate pedicellariae are small ; the valves are curved at the end, 

 which is somewhat constricted, and have only two to four short teeth, sometimes none at 

 all (Plate IX, fig. 18). Along the sides of the valves there are usually some rather coarse 

 serrations. The tridentate pedicellariae, which do not reach any large size, only ca. 

 0-5 mm. length of head, have broad simply leaf-shaped valves (Plate IX, fig. 17). There 

 are no two-valved pedicellariae. The triphyllous pedicellariae are just like small tri- 

 dentate ones. 



It is quite evident that this form cannot be referred to any of the rather numerous 

 species of the genus Abatiis hitherto known. One of these species was insufficiently 

 known, viz. A. elongatus (Koehler), the description and figures of this species given by 

 Koehler in his record of the Echinoderms of the Scotia Expedition (Trans. Roy. Soc. 

 Edinb., XLVi, 1908, p. 618, pi. xvi, figs. 145-58) being not all that could be desired. Thus 

 nothing is said about the important character whether subanal tube feet are present or 

 not. As one of the co-types has very kindly been sent me for re-examination from the 

 Edinburgh Museum, I take the opportunity of supplying here some information of this 

 species; from this it appears that A. ehngatiis is a distinct species, not identical with 

 A. Agassizii, as I formerly suggested (Swedish South Polar Exped. Echinoidea, p. 86). 

 The specimen is unfortunately badly broken and the exact number of the subanal tube 

 feet cannot be stated, but there are at least three of them. The labrum ends opposite 

 the second adjoining ambulacral plate. The figures of the pedicellariae given by Koehler 

 are rather crude, so I have taken the opportunity of giving some new figures of them 

 (Plate IX, figs. 12-16). It was particularly Koehler's fig. 155, said to represent a rostrate 

 pedicellaria, that I found strange and remarkably different from the rostrate pedi- 

 cellariae of other species of Abatiis. They proved to be tridentate pedicellariae of the 

 characteristic restricted form often occurring with two valves (here only three-valved 

 samples were found) (Plate IX, fig. 16). The rostrate pedicellariae are of quite another 

 shape (Plate IX, fig. 14) and were overlooked by Koehler. The characters of the pedi- 

 cellariae show beyond doubt that the present species is entirely diflFerent from Koehler's 

 " Hemiaster" elongatus} 



Of the other species of Abatus with bidentate globiferous pedicellariae, A. bidens, 

 Mortensen, A. Shackletoni, Koehler, A. Agassizii (Pfeffer), and A. ingens, Koehler, the 



1 The species name elongatus was changed by Thiery into Koehleri, because a (fossil) Hemiaster elotigatus 

 had already been described. Since, however, Koehler's species does not belong to Hemiaster, but to the genus 

 Abatus, there is no need to change the specific name. In this I quite agree with Koehler (Austral. Antarct. 

 Exped. Echinod. Echinoidea, p. 55). 



