i. 
REPORT ON THE CRINOIDEA. 309 
statement concerning Pentacrinus asterius and Pentacrinus miilleri.1 He likewise 
repeated most of his original description of Pentacrinus decorus as a diagnosis of Penta- 
crinus miilleri, with a reference under the latter name to the specimen which he had 
before him when describing Pentacrinus decorus. He stated that the two outer radials 
of Pentacrinus asterius were united by syzygy, and further added that “the arrange- 
ment of the joints and the syzygies in the eup is the same in Pentacrinus miilleri as ini 
Pentacrinus asteria, only the syzygy between the second radial and the radial axillary is 
not so complete.” This passage obviously refers to a ligamentous articulation as distin- 
guished from a true syzygy on the one hand, and from a muscular joint on the other ; 
and it is by no means in accordanee with Liitken’s very positive statements as to the 
presence of a true syzygy between the two outer radials of Pentacrinus miilleri. Neither 
does Sir Wyville’s deseription of the nodes as occurring about every twelfth joint agree 
with Liitken’s diagnosis, which records only four to ten internodal joints in Pentacrinus 
miillert. As a matter of fact there are eleven or twelve internodal joints in Pentacrinus 
decorus, and there is no syzygy at all between the two outer radials, but only a bifascial 
articulation such as occurs in the majority of the Neocrinoidea, and has often been 
wrongly spoken of as a syzygy, though clearly distinguished from it by Miller. This is 
shown in figs. 3 and 6 on Pl. XXXIV., a copy of which was lettered “ Pentacrinus miilleri, 
Oersted,” by Sir Wyville Thomson. I cannot but think, however, that if he had lived to 
work out the “ Blake” collection more fully than he was able to do before his health gave 
way, he would have retaimed his original views as to the distinctness of his Pentacrinus 
decorus from Pentacrinus miilleri, Oersted. The result of this confusion was that the 
numerous specimens of Pentacrinus decorus which were dredged by the “ Bibb” and the 
“Blake” in the Gulf Stream and in the Caribbean Sea were referred to Pentacrinus 
miillert by Pourtaleés and Agassiz.” The two species have really no sort of resemblance 
to one another, differing in all the characters of the stem, the cirri, the calyx, and the 
arms. 
The foregoing description is based upon an examination of ‘four specimens from the 
“Blake” collection, two purchased by Sir Wyville Thomson from Mr. Damon, one in the 
collection of Sir Rawson Rawson, and lastly that in the Museum of the Geological 
Society of London, which is mentioned by both Miller and Miiller as Pentacrinus caput- 
Meduse. 
Pentacrinus miilleri is readily distinguished from Pentacrinus asterius, which is its 
nearest ally, by the shortness of the internodes and the modification of the hypozygal 
joints, which, however, is far less marked than im Pentacrinus decorus. The basals 
generally form a complete ring ; while the branching of the arms is much more regular 
1 Proce. Roy. Soc. Edin., vol. vii. p. 766; and The Depths of the Sea, pp. 484, 435; see also The Atlantic, vol. ii, 
p. 126. 
2 Bull. Mus. Comp. Zool, vol. i. p. 357 ; Ibid., vol. v. pp. 56 and 214; Ibid., vol. vi. p. 296. 
