100 ME. P. H. CARPENTER ON THE GENUS ACTINOMETEA. 



fig. 4(1, b.f) are well developed and somewhat lancet-shaped in form, as in var. 1 

 (PI. YI. fig. 13, b.f, fig. 15, b.g). 



In var. 2, and still more in var. 3, the mode of union of the hars of the basal bridge 

 (figs. 19, 22 b, b.b) with one another and with the basal rays (S), is seen very distinctly 

 at the central end of the latter; much more so than in Act.pectinata (PL V. fig. 8 b), in 

 which, as in the other specimens figured (PI. V. fig. 3 ; PI. VI. figs. 4, 11, 13), the 

 various elements of each compound basal are so completely united, that the lines of 

 unction between them become almost indistinguishable. 



(§ 68) The complicated condition of the basals described above in Actinometra is not 

 altogether peculiar to this genus, as I was first inclined to believe ; for in Ant. Eschricldii 

 a basal star may be developed to a greater or less extent. In his paper on JPhanogcuia 

 Loven gives a diagram 1 of the dorsal aspect of the pentagonal base of the calyx of this 

 species for comparison with that of Thanogenia. It shows five large rays extending 

 from the periphery of the rosette to the outer angles of the radial pentagon, with the 

 constituent elements of which they alternate in position ; and in the text he speaks of 

 them as belonging to the rosette. Unfortunately, his paper is written in Swedish, so 

 that I have been unable to ascertain precisely what his views were with respect to the 

 homologies of these rays. 



His figure also shows five radial openings on the dorsal surface of the pentagonal 

 base, which correspond with the dorsal openings of the radial axial canals in Aid. rosacea 

 (PL IV. fig. 1G, Q). 



In neither of the two specimens of Aid. Eschrichtii which I have been able to 

 examine do these openings exist, so that they are probably somewhat uncertain in their 

 occurrence, as in Ant. celtica (PL IV. figs. 3, 7) ; and in neither of these specimens is 

 the basal star developed to any thing like the extent that it is in the specimen figured by 

 Loven. In one (PL IV. fig. 10, S) the rays are excessively small and inconspicuous, 

 only extending for a very short distance along the dorsal interradial furrows (d.i.f), 

 while the corresponding basal grooves on the interradial elevations of the centrodorsal 

 piece are also very slightly developed (fig. 11, b.g). The basal bridge also, connecting 

 two successive rays of the basal star, is barely traceable around the inner margin of the 

 radial pentagon (fig. 10, b.b). 



In the other specimen which I examined the basal rays were somewhat better 

 developed, occupying a larger portion of the dorsal interradial furrows, and extending 

 further outwards towards the margin of the radial pentagon ; although still remarkably 

 slender and delicate, somewhat as in Act. Solaris (PL V. fig. 3, S), and by no means so 

 large as in the specimen figured by Loven 2 . 



The interior of the calyx of Ant. Eschrichtii is much simpler than that of Actinometra, 



1 Loc. cit. p. 230, m. 



2 Sinco the above lines were written, I have examined several other specimens of Ant. Eschricldii. None of 

 them have the radial openings above mentioned, nor arc the rays of the basal star so large as in the specimen figured 

 by Loven ; but they arc always present, though less regularly developed than in Actinometra. Further, ray work on 

 the 'Challenger' Comatulce has brought out the fact that a basal star is nearly always present in Antedon as well as 

 in Actinometra, so that the British species (Ant. rosacea, Ant. celtica) are remarkable for its absence, rather thun 

 Ant. Eschrichtii for its presence. 



