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



of Antedon loveni, 1 which was described by Bell, though the fact seems to have escaped 

 his notice, for he makes no mention of it. 2 The cirri and one arm are lost; but only one 

 of the remaining nine arms has a pinnule on the third brachial. The great size and 

 the elongated joints of the second and third pinnules in Antedon loveni are sufficient, 

 however, to prevent any confusion between it and Antedon informis. 



Another species in which the third brachial bears no pinnule is Antedon manca 

 (PI. XLIV. figs. 2, 3), which will be described further on in the Bidistichate group. 



Apart from the absence of the pinnule on the third brachial, Antedon informis is also 

 distinguished by the long interval between the first and second syzygies, 3 and by the 

 peculiar minute spinelets on the cirrus-joints. I know of no described species with which 

 it is likely to be confounded. 



All the ten-armed species of Antedon which were obtained by the Challenger and 

 " Porcupine " have now been considered, with one exception. This is the singular form 

 which I have called Antedon balanoides (PI. XXXIII. figs. 6, 7); and there are four 

 other species besides it which do not seem to fit into any of the groups established above. 

 All but one inhabit the Eastern Archipelago, and for the present they may be classified 

 as follows : — 



A. The second and third brachials have pinnules. 



I. The first pinnule is the largest. Cirrus-joints have two dorsal 



spinelets, ....... bidens, Bell. 



II. The lower pinnules tolerably equal. 



Twenty cirrus-joints without spines ; syzygial interval three or 



four joints, ...... adeems, Lamk., sp. 



Twenty-five to thirty-five spiny cirrus-joints ; syzygial interval 



nine or ten joints, ...... Ixvijnnna, Carpenter. 



B. The second and third brachials have no pinnules. 



Sixty cirri of thirty-five to forty joints on a conical centro-dorsal, . 1. balanoides, n. sp. 

 Twenty cirri of about twenty joints, ..... defecta, Carpenter, MS. 



C. The third, fourth and fifth brachials have no pinnules. Eight or ten 



cirri of twelve joints, ...... impinnata, Carpenter, MS. 



The last of these is a little species which was obtained at Mauritius by Professor 

 Mobius, who was kind enough to show it to me when I visited Kiel ; and I found it to 

 be serving as host to Myzostoma excisum and Myzostoma carinatum, von Graff. 



1 " Alert " Report, p. 158, pL x. fig. C (non A). 



2 Bell's figure is also incorrect ; for the pinnules of the second, fourth, and sixth brachials are represented as being 

 placed on the inner instead of on the outer side of the arm. A similar error occurs in the figure of Antedon ■pumila on 

 the same plate, in which the first, second, fourth, and sixth, &c, brachials are all represented as bearing pinnules on 

 the inner side of the arm, an arrangement which never occurs in any Crinoid. 



3 The central arm represented in the figure has a syzygy in the fourth brachial as well as in the third. 



