REPORT ON THE CRINOIDEA. 165 



length of the second pair of pinnules, which are nearly equal to the first ; while the back- 

 ward projection of the axillaries into the second radials is more marked in both these 

 types than in Antedon phalangium, more especially in Antedon hystrix. 



Antedon phalangium serves as host to two species of Myzostoma, viz., Myzostoma 

 pulvinar and Myzostoma alatum. The former is only known from the Minch ; but the 

 latter occurs both there and in the Atlantic, off Cape Mondego, and also in the 

 Mediterranean where it was dredged off Carthagena. It is curious, however, that no 

 Myzostoma was obtained with the great number of individuals which were met with by 

 the "Porcupine" on the Tunis coast. 



2. Antedon hystrix, n. sp. (PI. XXVII. figs. 21, 22 ; PI. XXVIII. figs. 4, 5). 

 Specific formula. — A. t-. 



1884. Antedon hystrix, P. H. Carpenter, Proc. Roy. Soc. Edin., 1884, vol. xii. p. 365. 



Centro-dorsal hemispherical or subcorneal, bearing fifty or sixty dimorphic cirri. The 

 longest, which are round the margin, reach nearly 50 mm., and consist of about forty- 

 five smooth joints, most of which are longer than wide. The smaller cirri nearer the 

 dorsal pole have only about twenty-five joints, which are relatively shorter and overlap 

 slightly. 



First radials partially visible at the angles of the calyx ; the second comparatively 

 short and often not visible at all in the middle line of the ray, owing to their being very 

 deeply incised to receive the strong backward projections of the axillaries. These are 

 quadrate in form, with their sides curved, especially the anterior pair, and they are 

 distinctly longer than wide, sometimes seeming to overlap the centro-dorsal ; but much 

 less than half the length is in front of the line joining their lateral angles. The first 

 brachials have long outer sides and very short inner ones, but like the second radials are 

 almost invisible in the middle line of the arm, owing to the very strong backward 

 projections of the irregularly triangular second brachials, which nearly reach the axillaries. 

 Both on these joints and on the rudely oblong third brachials, which are much wider than 

 long, the pinnule-socket is placed nearer the dorsal surface than usual. The next 

 following joints are short and quadrate, with curved proximal and distal edges ; and the 

 pinnule is on the shorter side, the longer being marked by a backward projection. 

 Syzygies in the third and eighth brachials, and afterwards at intervals of three or four 

 joints. Ten arms ; the lower brachials triangular and slightly wider than long, slowly 

 becoming quadrate, and somewhat elongated towards the arm-ends. 



The first pair of pinnules (on 2nd and 3rd br.) are much longer and stouter than 

 the next pair. They reach nearly 15 mm. and consist of some thirty smooth joints, the 

 first six of which are short and nearly square. The second pair have but eighteen or 



