MUSEUM OF COMPARATIVE ZOOLOGY. 171 



form a complete ring ; while the branching of the arms is much more regular 

 than in P. asteria, and there are fewer joints between the successive axillaries. 



P. decorus Wtv. Thomson. 



Stem slender, rarely exceeding 4 mm. in diameter, with 7-16 (usually 11 or 

 12) internodal joints. The nodal joints are generally somewhat enlarged, with 

 circular cirrus-sockets which do not nearly reach tlieir upper edge, but extend 

 well down on to the hypozygal joints. 



Slender cirri composed of 25-35 joints, and reaching 28 mm. in length. 



Lowest limit of the interarticular pores from the ninth to the eleventh node. 



The two outer radials united by a ligamentous articulation. Kay-divisions 

 rather irregular. Primary arms of 2-7 (distichal) joints, of which the first two 

 are united by a ligamentous articulation, the second bearing a pinnule, while the 

 last two often form a syzygy. Secondary arms of 1-9 (palmar) joints, which 

 are very variable in their character. The second free brachial is usually a syzy- 

 gial joint. The next syzygy from the eighth to the thirtieth brachial, after 

 which an interval of 5-11 joints between successive syzygies. 



A pinnule on the first joint after the last axillary. Pinnule joints laterally 

 compressed, those at the base of the lower pinnules being rather broad, but the 

 following ones are elongated. 



Examples of this type were dredged by the " Blake " at the following sta- 

 tions : — 



1877-78. Off' Havana. 175 and 177 fathoms; very abundant. 

 1878-79. Nos. 155 and 156. Off Montserrat. 88 fathoms. 

 No. 269. Off St. Vincent. 124- fathoms. 



Eemarks. — The distinctness of this species from P. asteria was first recognized 

 by Mr. Damon of Weymouth, who procured an example of it from the seas of 

 the outer Antilles. Its occurrence was recorded by the late Sir Wyville Thom- 

 son in a popular article on " Sea Lilies," which was published in the " Intel- 

 lectual Observer" for August, 1864, but no formal description of it has since 

 appeared. At that time Sir Wyville seems to have been unacquainted with 

 the description of P. mUlhri by Oersted, published six years previously, for he 

 spoke of P. asteria and P. decorus as "the only two known living species" of 

 Stalked Crinoids. But in the following year* he referred to P. miilleri as well, 

 Llitken's memoir having appeared in the interval ; so that he evidently regarded 

 r. decorus and P. miilleri as separate species. Later on (1872), however, he 

 seems to have come to the conclusion that his P. decorus was identical with 

 Oersted's species. For, having previously said that P. asteria and P. decorus 

 were the only two known living species of the genus, he made nearly the same 

 statement f concerning P. asteria and P. mUllcri. He likewise repeated most 



* Phil. Trans., Vol. CLV. p. 542. 



t On the Crinoids of the " Porcupine " Deep-Sea Dredging Expedition, Proc. Roy. 

 See. Edinb., Vol. VII. pp. 765-767 ; and "The Depths of the Sea," pp. 434-442. 

 See also " The Atlantic," Vol. II. p. 126. 



