RErOKT ON THE ASTEROIDEA. 499 



two sides. The tissue of the lateral web is thickened along the margin, especially over 

 the extremity of each spine, to which it gives a rounded capitate appearance, the web 

 having the very faintest trace of incurving between the spinelets. The thickening of th? 

 membrane just mentioned is much more pronounced in the arm-angle, where all indenta- 

 tion of the web is obliterated and indications are present of a tendency to excrescent 

 growth. A further faint line of thickening can be made out at the union of the abactinal 

 and actinal tissues, which occurs just within the margin, especially round the shaft of the 

 spines. 



Colour in alcohol, greyish white. 



Locality. — Station 158. South of Australia, 1099 miles south-west of Cape Otway. 

 March 7, 1874. Lat. 50° 1' 0" S., long. 123° 4' 0" E. Depth 1800 fathoms. Globigerina 

 ooze. Bottom temperature 33°"5 Fahr. ; surface temperature 45°"0 Fahr. 



Remarks. — Hymenaster formosus may be recognised at once by the small, uniform, 

 rounded, and almost wart-like elevations on the abactinal surface ; and by the single, large, 

 and uniformly spaced spiracula — a character which readily distinguishes it from the other 

 species having only one spine in the adambulacral armature. 



3. Hymenaster pergamentaceus, Sladen (PI. LXXXI. tigs. 1 and 2 ; PI. LXXXIII. 

 figs. 1-3). 



Hymenaster pergamentaceus, Sladen, 1882, Journ. Linn. Soc. Lond. (Zool.), vol. xvi. p. 215. 



Marginal contour stellato-pentagonal ; interbrachial arcs moderately indented, although 

 the actual angle is masked by an abnormal development of the actino-lateral spines, which 

 meet there and form a peak and an irregular excrescence of the web. The minor radial 

 proportion is about 60"5 per cent. R= 66 mm. ; r= 40 mm. (approximately). The radial 

 areas are well defined from the lateral fringe, and taper rapidly at the extreme tip to a 

 fine, slightly produced extremity, which is recurved. The " fringe " is more or less irre- 

 gular, owing to the thickening at the margin and abnormal growth, and is only slightly 

 indented or festooned between the spinelets, the tips of which are rounded and thickened. 



The supradorsal membrane is thin, smooth, and vellum-like. The paxillse are compa- 

 ratively few in number and bear five to eight spinelets, which are robust and widely 

 expanded. Although these are in a certain sense regular in their distribution over the 

 area, no definite pattern of arrangement is produced. The extremities of the spinelets do 

 not protrude through the membrane, but simply elevate it into small eminences ; and 

 owing to the thinness of the supradorsal membrane, the outlines of the spinelets which 

 form each paxilla may be more or less clearly discerned. The rays are well defined, and 

 no paxillaa-spiuelets occur in the intermediate iuterradial portion of the lateral fringe, 

 nor do any spinelets encroach upon a narrow clear space which runs down the median line 

 of each radius. The fibrous bands are very numerous and closely massed together ; 



