REPORT ON THE CRINOIDEA. 269 



the basals, as it crosses the former at a variable distance from their lower angles. In a 

 few cases, however, the basiradial suture is more uniformly horizontal, and not marked 

 by alternate elevations and depressions (PI. X. fig. 3) ; so that the furrow really does 

 indicate the line of separation between the basals and radials. But this is far from being 

 the case in Prof. Perrier's drawing of the Democrinus calyx. 



The fragmentary condition or absence of the arms in his specimens is nothing unusual. 

 Only one-third of all the individuals of Rhizocrinus rawsoni which I have examined have 

 any arms at all, including the young form represented in PI. LIII. fig. 7. There may, 

 however, be as many as one hundred and twenty joints, or rather sixty syzygial pairs, 

 with pinnules on all but the first three or four. But they are very apt to break away at 

 the syzygy in the first brachial, which Perrier speaks of as an articulation between a 

 radial axillary and the lowest arm-joint. This had happened in two of his three speci- 

 mens of Democrinus, which are " totalement depoux'vus de bras; le troisieme n'en presente 

 que des restes tres courts, d'apres lesquels il est aise de voir que les bras devaient ^tre 

 extremement peu developpes." The drawing of this individual which he has sent me 

 shows that its longest arm-fragment consists of only five joints, i.e., two composite 

 brachials and the hypozygal of a third. This fully accounts for the absence of pinnules, 

 which never appear below the third epizygal in any Rhizocrinus ; and I have little doubt 

 that further research will prove the existence of properly developed, pinnule-bearing arms 

 in the so-called Democrinus. But I do not suppose that they are quite as fully developed 

 as those of the Caribbean variety of Rhizocrinus rawsoni. This has a stem more than 

 twice the width of that of Democrinus; and it is generally more robust, though the 

 calyx is distinctly shorter and broader than in Perrier's type. 



The " Travailleur " specimens are of interest, both on account of their aberrant form, 

 and because they give another locality for Rhizocrinus rawsoni in the East Atlantic in 

 addition to the two discovered by the "Porcupine" in 1869; while the "Talisman" 

 met with another locality of the type during the dredgings of 1883.^ 



It is remarkable for its close resemblance to the Rhizocrinus londinensis from the 

 London Clay, isolated stem-j oints of which were referred by Forbes ^ to Bourguetic7-inus. 

 But a well preserved and very characteristic calyx has since been discovered, and is now 

 to be seen in the Natural History Museum at South Kensington. 



1 Dertiocrinus dies hard. Perrier's mistake about the condition of tlie basals in Rhizocrinus was pointed out in the 

 Ann. and Mag. Nat. Hist, ser. 5, voL xi., 1883, p. 334. Under these circumstances the character on which he relied as 

 distinguishing Democrinus from Rhizocrinus became non-existent ; and I therefore expressed my conviction that 

 Democrinus Parfaiti and Rhizocrinus rawsoni were identical. Perrier, however, appears to be of a different opinion, 

 for in the Preliminary Report of Mans. A. Milne-Edwards, the President of the "Talisman" Commission of 1883, 

 Democrinus is specially nientioned as one of the captures [Goinptes rendus, t. xcvii. p. 1392) ; while in the semi-official 

 account of the collection published in La Nature (No. 572, p. 391) by Mons. H. Filhol, also a member of the 

 Commission, particidar reference is made to Democrinus Parfaiti. As the addition of a new generic type to the family 

 BourgueticrinidiB is of considerable importance in many ways, Prof. Perrier's revised account of its characters will be 

 awaited with interest, both by zoologists and by pala;outologist3. 



2 British Tertiary Echinoderms, p. 36. 



