38 ON THE ECHINODERMATA OF THE 



running parallel with the furrow, and another, placed at right angles to this, forming 

 a radiating comb, which holds a transverse position in relation to the direction of the 

 ray. In the innermost or furrow series there are 3 to 4 spinelets to each plate, forming 

 a line frequently more or less oblique and curved in its position ; and their length at the 

 base of the ray is fully equal to two thirds of the breadth of the furrow at its widest 

 part. In the transverse series, the spinelets, which are 5-7 in number, are connected 

 at their base by a membranous skin ; they are stout, and the innermost spines are some- 

 what larger than those of the longitudinal series. 



The interbrachial spaces are very narrow, and either entirely naked or bearing 

 only a few small spine-groups resembling rudimentary papillae, irregularly disposed here 

 and there. 



The mouth-plates are broad and subtriangular, having a marginal fringe of large 

 robust mouth-spines upon their outer edges; the four or five innermost, which are directed 

 towards the actinostome, diverge only slightly from one another ; whilst the following 

 five or six, which are somewhat smaller, radiate sideways, and interlock more or less 

 deeply with those of the neighbouring mouth-plate. From the surface of each mouth- 

 plate, and standing perpendicularly thereto, midway between the outer edge and the 

 median suture, is a secondary series of two or three large robust spines. 



Size. Large examples are on record measuring 280 millims. in diameter ; but the 

 northern specimens are usually very much smaller, seldom exceeding 100-150 millims., 

 the largest individual from Discovery Bay being only 93 millims. 



Colour. According to Liitken the Greenland specimens are generally of a deep 

 fiery red ; but in the more southern portion of its area of distribution the species is 

 frequently more or less mottled with lighter shades, whilst the general tint is often 

 inclined to shades of purple. Small examples are white or straw-coloured. All colour 

 is usually bleached in specimens preserved in spirit. 



Habitat. C. papposus frequents a hard-ground locality, its bathymetrical range 

 extending from low water to great depths, as indicated in the citations of occurrence 

 given below. 



Premature Form. In a young stage the ossicles of the abactinal network are more 

 widely spaced, and consequently the paxillse, which at this age are only found at the 

 intersections, stand further apart and are fewer in number ; whilst the paxillse, although 

 composed of a smaller number of spinelets, are proportionately larger in size when 

 compared with those on the adult Starfish. The large compressed lateral paxillse are 

 fewer in number, as are also the papulae. Consequent on the smaller number of ray- 

 elements there are fewer transverse ambulacral combs ; and these themselves are made 

 up of only 3-5 spinelets (the number varying according to age), whilst not more than 

 two spines of the longitudinal furrow-series are present. The mouth-spines are, in like 

 manner, less striking, both in character and number. 



Variations. The variations which are the most strikingly conspicuous in this 

 species are those that affect the relative proportions of the rays to the disk and the 

 character of the dorsal paxillse. Dr. Liitken * has already remarked on the existence 



* Vid. Mcddol. N. Forening i Kjobcnhavn, 1857, p. 42. 



