170 ACTINLE OF ALBATROSS EXPLORATIONS MCMURRICH. - 



can scarcely be proper to associate with tliem L*aractids. In cases 

 like tb is where the delinition is imperfect we have to interpret the 

 geiuis from the forms which have been assigned to it and not vice versa., 

 and a more perfect definition of the genns Dysactis will include a men- 

 tion of the occurrenc<' of acontia and cinclides. (See Appendix p. 209.) 



18. Actinostola excelsa, sp. no v. 

 PLatft xxvi. Figs 53-56. 



No. 690. Station 2770. i.at. 48^ 37' S. ; long. GTv 46 W. Depth, 5S fathoms. One 



specimen. 

 No. (W8. Station L'77L La.t. 51^"' 34' S. ; h.ng. OS- 00' W. Depth. 50^ fathoms. Two 



specimens. 



This very striking form (PI. wvi, Fig. 53) measures about 6"" in 

 height and from 5.5 to <>''"' in diameter. The base is evidently 

 adherent and the limbus is not folded over it, as Avas the case in A. 

 CixUosa. 



The column is cylindrical, narrowing slightly towards the margin, and 

 is apparently capable of little contraction. Its walls are firm, and for 

 the most part smooth, though in contracted specimens irregular longi- 

 tudinal ridges are to be seen below the margin; these, however, seem 

 to be due to the state of contraction. The ectodeiiii of the column has 

 a pale brown or buff color; where it has been macerated away the sub 

 jaceut mesogkea is seen to be cream white. The sphincter muscle 

 (PI. XXVI, Fig. 54) is fairly strong, but nevertheless is unable to over- 

 come the resistance olfered by the firmness of the column mesoglffia, so 

 that in none of the specimens are the tentacles concealed from view. 

 In sha])e the sphincter differs markedly from that of A. caUosa. It 

 forms a delicate network, occupying almost the entire thickness of the 

 mesogloea in its upper half, and its inner surface passes into the gen- 

 eral circular musculature of the column wall. There is no tendency 

 for the nuiscle cavities to arrange themselves in longitudinal rows as in 

 A. caUosd^ but rather in horizontal lines perpendicular to the surface of 

 the column. The column wall is less thick in its uppermost ])art than 

 a little lo\\('r (h»wn,and consequently the thickest portion of the sj^hiuc- 

 ter is below its uppermost edge, in fact, almost half-way down. In its 

 lower part it is thin, lying close to the endodermal surface of the meso- 

 gkea, and is i)rolonged downwards some distance in this condition, 

 gradually beconling lost in the nuiscle ])rocesses of the <'ircular muscu- 

 lature of the column wall. 



There is no definite margin, the tentacles occurring at the junction of 

 the disc and c(»lumn wall. 'IMiey arc rather nunuMons, numbering per- 

 hajjs one hundred and ninety two, and are short and stcnit, with pores at 

 their extremities. They are longitudinally fluted, and also transversly 

 grooved, so tliat the surface seems much corrugated. The mesogbea 

 of the tentacles is almost entirely occupied by the longitudinal nuiscles 



