114 Dr. P. H. Carpenter on some Points in 



Stalked Crinoids is Pentacri7ms itself. Can he name a single 

 recent species of this genus in which the syzygial faces are 

 marked by elevated ridges and furrows radiating from the 

 central canal as in the Comatuloe.'i In by far the greater 

 number of cases the joints are perfectly plain, without any 

 indications of sculpture at all*; but there is sometimes a 

 slight trace of striation round the margins of apposed syzy- 

 gial surfaces. Exactly the same thing often occurs on the 

 apposed surfaces of the basals and radials respectively, and 

 on the lateral surfaces of the radials where they are closely 

 united by suture. Sometimes, indeed, there is a faint indi- 

 cation, over part of the syzygial face, of a radial striation 

 which extends inwards towards the central canal but dies 

 away before reaching it, and is not due to the presence of 

 elevated ridges, as in the Comatulce. The best instance of this 

 which I know is on the apposed syzygial faces of the radials 

 of a Pentacrinus asterms which were figured by Sir Wyville 

 Thomson in the ' Challenger ' Report f ; but his figure of the 

 " pourtour de la syzygie " on the dorsal aspect of the ray 

 shows it to be absolutely devoid of all trace of pores, as is 

 really the case. I have seen many other indications of radial 

 striation, both in this and in other species of Pentacrinidse ; 

 but they are merely superficial markings on the joint- faces, 

 and are altogether different from the well-defined radiating 

 ridges on the syzygial faces of a Gomatula arm-joint, which 

 can be stripped off entire when the syzygy is split open after 

 decalcification. It is, of course, possible that Prof. Perrier may 

 have obtained a section through a syzygy in a Pentacrinus-diYm. 

 with better-defined radiating ridges and intervening furrows 

 than any which I have seen in this genus ; but I doubt it. 

 The dredgings of the ' Talisman ' yielded several specimens 

 of Pentacrinus Wyville- Thomsoni \ and if Prof. Perrier has 

 not cut sections through a syzygy of this species, it would 

 have been better for him to have done so before making a 

 general statement respecting the syzygies of Stalked Crinoids 

 which harmonizes so admirably with his previously expressed 

 views. I have several sections through the largest syzygy 

 in this species, viz. that between the second and third radials ; 

 and there is absolutely no trace either of the radiating cavities 

 or of the powerful muscles which Prof. Perrier describes in 

 the ''Encrines." I can say the same of the arm-syzygies in 

 Pentacrinus decorus ; and if the smooth appearance of the 

 syzygial faces is any guide, there is not a single recent mem- 



* Zool. Chall. Exp. part xxxii. pp. 4, 2^A, pis. xxvi. & xxxvii. 

 t PI. xii. figs. 17, 18, 21. 



