REPORT ON THE CRINOIDEA. 1G7 



dredged by the " Varna " in the Kara Sea ; and by the kindness of Mr. F. Nansen, 

 Conservator of the Bergen Museum, I have been able to examine half-a-dozen individuals 

 of the same type which was met with in abundance by the Norwegian North Atlantic 

 Expedition near Spitzbergen. These last come nearest to Antedon hystrix in their 

 general robustness, the more northern forms of the type being generally smaller, except 

 as regards the cirri. These seem to be a little less smooth and to reach a greater length 

 in Antedon prolixa than in actually larger individuals of Antedon hystrix. Thus, for 

 example, an imperfect cirrus of Antedon prolixa, with the extremity missing, which was 

 measured by Sladen, reaches 58 mm.; while I have not found any cirrus exceeding 50 mm. 

 in Antedon hystrix. This, however, is a point of minor importance. The great difference 

 between the two types lies in the characters of the two outer radials and of the two lowest 

 brachials. The second radials of Antedon prolixa are but little more incised for the 

 axillaries than those of Antedon phalangium, with which species Sladen has well compared 

 it, though the two differ altogether in the proportions of the second pair of pinnules ; 

 while the axillaries of Antedon prolixa are very regularly quadrate and as wide as or wider 

 than long, the line joining their lateral angles dividing them into two nearly equal parts. 

 In Antedon hystrix, however, they are longer than wide, and project so deeply backwards 

 into the second radials that they sometimes seem to overlap the centro-dorsal 

 (PL XXVIII. figs. 4, 5). The second radials are therefore almost invisible in the middle 

 line of the ray, though when seen from the side they appear to have a considerable relative 

 length and to form a projecting tubercle together with the axillaries, as is well shown in 

 PI. XXVIII. fig. 4. The shape of the axillaries therefore is not " very regularly quadri- 

 form" as described by Sladen in Antedon prolixa, but more pear-shaped, with much less 

 than half the length of the plate in front of the hue joining the lateral angles, a condition 

 exactly the reverse of that which occurs in many forms of Antedon eschrichti. In like 

 manner the second brachials of Antedon hystrix are relatively larger, and project further 

 backwards into the first than in Antedon prolixa, so that there is a more distinct tubercle 

 on the line of junction. 



The " Triton " specimen of Antedon hystrix was dredged in about lat. 60° 30' N., and 

 Antedon prolixa was obtained by the Norwegian North Atlantic Expedition in lat. 76° X., 

 near Spitzbergen. It is of course possible that future explorations in the intervening area 

 of the Atlantic may discover a series of forms intermediate between those which now 

 appear distinct ; and I should not be very greatly surprised if this should turn out to be 

 the case. AVere they really identical, Antedon prolixa would present just the opposite 

 condition to Antedon eschrichti, its northern variety being less robust than that found in 

 lower latitudes. The small examples of Antedon prolixa from the Kara Sea (lat. 71° N.) 

 are, however, very different from Antedon hystrix. The "Triton" specimen of the 

 latter type presents a very curious malformation, which is shown in PI. XXVIII. fig. 5. 

 The two second brachials of one ray jointly support a single arm, so that there are only 



