96 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



the much plated visceral mass of an Aniedon common at Cape York" and referred to 

 two figures (pi. 55, figs. 3, 4) showing two visceral masses of Antedon multiradiata 

 [=Zygom,etra microdiscus}. Some pages further on he said that the original of Hypo- 

 nome sarsii was the disk of a plated Antedon, "very probably of this species, Antedon 

 multiradiata." In his memoir on the genus Actinometra published in 1879 Carpenter 

 remarked that we are as yet Unacquainted with any comatulids in which the elements 

 of the IBr series are united by syzygy and there are more than 10 arms. This remark 

 is followed by a reference to a footnote, and in the footnote he said that in the Chal- 

 lenger collection there are three comatulids that answer to this description. One of 

 these three is the present species. 



In 1882 Prof. F. Jeffrey Bell published a specific formula for a new species he called 

 Antedon microdiscus. In 1884 he described and figured this new species, which had 

 been obtained by the Alert at Port Molle, and mentioned a specimen in the collection 

 of the British Museum from Nicol Bay. In 1884 Carpenter noted that in some species 

 of Antedon with an incised disk the anambulacral plates are somewhat squamous, 

 with a tendency to overlap one another. He figured two disks illustrating this tend- 

 ency which had been dredged at Cape York as isolated disks. He said that these 

 disks probably belong to Antedon multiradiata, entire individuals of which (unde- 

 scribed) species had been dredged together with them. He went on to say that in 

 these disks 



The edges of the interpalmar areas rise rather sharply toward the ambulacra, which are marked 

 by strong ridges with indications of a median groove visible upon their upper surface. The food- 

 groove beneath is really comparatively deep, with its edges plated somewhat regularly and turned in 

 towards one another. This is very marked in the immediate neighborhood of the peristome, which is 

 thus completely closed. It is concealed in the smaller specimen by the large and prominent anal 

 tube which projects forwards over it. 



In 1884 Prof. Ludwig von Graff described the myzostomes that Carpenter had 

 found upon the specimens from Challenger station 187 and had sent to him, giving 

 Antedon multiradiata as the name of the host. 



In 1887 Carpenter discussed the distribution of the sacculi in Antedon microdiscus 

 and in his new species A. multiradiata from Cape York, and in the same year von 

 Graff recorded the myzostomes that Carpenter had found upon a specimen of A. 

 microdiscus from Challenger station 186. 



In 1888 Carpenter described Antedon multiradiata in detail from two imperfect 

 specimens and several isolated disks, which had been dredged by the Challenger at 

 station 187. In the remarks under this species he said that Hyponome sarsii is nothing 

 but one of these Antedon disks covered with a well-developed calcareous plating, both 

 at the sides of the ambulacra and in the mterambulacral regions. He said that it is 

 not unlikely to have been the disk of Antedon multiradiata which was dredged in this 

 condition at Challenger station 187, as it has a more extensive plating than the disk of 

 Antedon microdiscus. 



At the same time Carpenter described a specimen of Antedon microdiscus that had 

 been dredged by the Challenger at station 186. This was the only specimen of this 

 species dredged by the Challenger, and it did not come into Carpenter's hands with 

 the rest of the Challenger collection, for it had been given by Sir Wyville Thomson to 

 the National Museum at Stockholm where Carpenter found it during his visit to that 

 museum in August 1886. Later Professor Love'n kindly sent it to him in England for 



