156 THE VOYAGE OF H.M.S. CHALLENGER. 



calyx than might have been expected ; but its early age is indicated by the great relative 

 length of the arm-joints and the small size of the proximal pinnules (PI. XXVI. 

 fig. 1). 



This species ranges slightly further north than Antedon eschrichti, having been 

 obtained at Discovery Bay (lat. 81° 41' N.) together with Antedon prolixa, and 

 at Franklin-Pierce Bay (lat. 79° 25' N.) together with Antedon eschrichti, which was not 

 met with at the higher latitude. The bathymetrical range is greater, however, in 

 the larger form, which extends down to 632 fathoms, while Antedon quadrata was 

 not found below 466 fathoms in the same region of the Feeroe Channel ; the nearest 

 approach to this depth being the "Valorous" station in Davis Strait (410 fathoms). 



The three "Triton" specimens are all of them small, like those of the "Tegetthoff" 

 and "Valorous"; while they have a stiff er and less feathery appearance than the 

 larger ones obtained further north by the " Alert " and " Willem Barents." 



In fact they more nearly resemble the small individual figured by Sladen 1 in 

 their general characters. The dorsal processes on the lower joints of the basal pinnules 

 are less prominent than usual ; while the peculiar characters of the first two pinnule-joints 

 in the outer parts of the arms are by no means so marked as in larger individuals. 



The only Arctic species that approaches Antedon quadrata in the great disproportion 

 between the second and third pinnules is Antedon barentsi ; but it has much smaller 

 cirri with fewer joints, triangular joints in the middle of the arms, and the genital 

 pinnules protected by plates as in Antedon incisa, Antedon acoela, and other tropical 

 forms, though on a less massive scale. 



Like Antedon eschrichti, with which it is often associated, Antedon quadrata 

 officiates as host to Myzostoma gigas. 



4. The Tenella-groviTp. 



Long-jointed lower pinnules. 



The first three species on the list of those which I have included in this group, 

 Antedon phalangium, Antedon hystrix, and Antedon prolixa, have many affinities with 

 Antedon eschrichti and its allies, both in their distribution and in the characters of 

 their arms and cirri. 



Antedon hystrix and Antedon prolixa are exclusively cold-water species, not 

 having been obtained south of lat. 60° N.; though Antedon phalangium occurs in the 

 Mediterranean and in the East Atlantic as far south as the Seine Bank (lat. 33° 47' N., 

 long. 14° 1' W.). These species differ from the Eschrichti-growp, however, in the 

 characters of the lower pinnules, which, though often long, slender, and more or less 

 flagellate, consist of joints which are much longer than wide, as is particularly evident 



1 Op. cit,, pi. vi. fig. 5. 



