EEPORT ON THE CRINOIDEA, 29 



colonies et ramifies." I can, however, see no probability whatever in this supposition, 

 having met with no facts confirmatory of it either in any of the numerous roots of 

 Ehizocrinus and Bathycrinus which I have examined, or in the descriptions of these 

 genera by Sars and Danielssen. Neither is it supported in the slightest degree by what 

 we know of the embryology of the Crinoids. 



Prof. Perrier has suggested some further views of the morphology of the stem which 

 I find myself unable to accept. He begins by saying " De tons les Crinoides fixes actuels, 

 les Democrinus sont ceux chez qui les dimensions trausversales du cahce sont le plus 

 foibles jiar rapport au diametre du pddoncule." 



I am indebted to his kindness for the following measurements of his specimens — 



Length of the calyx from the terminal furrow to the top stem-joint, . . 9 mm. 



Maximum diameter of the calyx, . . . . . . . 2 „ 



Diameter of the stem-joints, . . . . . ■ . . 1 » 



That is to say, the diameter of the calyx does not exceed twice that of the stem-joints. 

 But at the time Prof. Perrier made the statement quoted above he had before him the 

 following measurements of the calyx and stem in three varieties of Rliizocrinus rawsoni — 



Basal tube. Stem-joints diameter. 



1. Blake, . . . . 5-5 x 2-50 mm. 2-25 mm. 



2. Challenger, . . . S'O x 2-00 „ 2-00 „ 



3. Porcupine, . . . 3'0 x 1-75 „ 1-25 „ 



Hence the maximum width of the calyx in the Challenger specimens of Rliizocrinus 

 rawsoni is the same as that of the largest stem-joints ; while the proportion is as 2 : 1 in 

 the so-called Democrinus, and this is not attained by the calyx, either of the " Blake " or 

 of the " Porcupine " specimens. It seems to me that the calyx of Democrinus is larger 

 relatively to the stem than in any of the Crinoids most nearly allied to it (instead of 

 being narrow as stated by Prof Perrier), who proceeds as follows : — "Si Ton songe que, chez 

 les Echinodermes libres actuels, le corps tout entier ne represente que le calice des 

 Crinoides fixes surmonte de ses bras, on est etonne de voir une partie qui est absolument 

 nuUe chez les representants des autres groupes prendre chez les Democi'inus un 

 developpement tel qu'elle represente cinq k six fois au moins le volume du corps propre- 

 ment dit. Ce fait seul nous avertit que le pedoncule doit Stre pris en grande consideration 

 pour la determination de la forme fondamentale des Echinodermes. Chez les Demo- 

 crinus, il produit un appareil radiculaii-e forme de rameaux articules ramifies ayant la 

 meme structure que lui-meme et presentant des dimensions superieures a celles des bras ; 

 cet appareil ne saurait etre davantage neglige au point de \mq morphologique, et Ton est 

 conduit t, considerer ses diverses branches comme ayant la meme valeur que le pedoncule 

 lui-meme dont elles ont la structure." 



A far better instance than Democrinus of disproportion between stem and head is 



