V. Botryocrinus. 397 



The proposed name of this species is one of those printed 

 by Salter : although not a good name, and although no 

 adequate description was given by Salter, yet I have adopted 

 it simply so as not to burden nomenclature with a synonym. 

 Salter did not profess to describe species in his Catalogue, and 

 all he said of Cyathocrinus decadactylus was " Ten single 

 arms, unbranched, and with very large thick tentacles." 

 This applies to not a single Cyathocrinus it is true, but it 

 applies to nearly every species of every genus of the Decado- 

 crinidas. Cyathocrinus quindecimalis was said to have 

 " Fifteen arms, like those of the last species, but with even 

 thicker tentacles." The specimen alluded to (PI. XILI. 

 fig. 13) shows, however, that this number of arms was a 

 misapprehension. The original specimens of both C. deca- 

 dactylus and C. quindecimalis belong to the species of Botryo- 

 crinus that I now proceed to diagnose. 



Specific Diagnosis. 



Cup elegant, rapidly widening above. K. projecting, with 

 rather narrow facet. Arms about six times length of cup, 

 two-branched, with rather stout pinnules ; sutures alternate in 

 direction. Proximal median plate of sac wider than high. 

 Ventral sac ridged, with plates, except at distal end, laterally 

 folded ; the distal end is almost straight. Stem slender ; 

 round or subpentagonal. 



Desckiption of Species. 



Dorsal cuj) of graceful appearance, owing to the concavo- 

 convex curve of its sides. Average measurements, based on 

 seven specimens, are : — Breadth at base 3*33 millim. ; breadth 

 at summit 8*36 millim. ; height 6*5 millim. 



Infrabasals 5, pentagonal, forming a very slight angle with 

 the column ; sometimes smooth, sometimes slightly rounded 

 or protuberant, and sometimes with a slight ridge along their 

 proximal margin. Average measurements, based on seven 

 specimens, are : — Height 1*91 millim. ; greatest width 2*17 

 millim. 



Basals ; 3 hexagonal and 2 heptagonal ; occasionally show 

 slight traces of axial folding*. Average measurements, 



* A very large number of Crinoids have the plates of the dorsal cup 

 folded or ridged along certain definite lines at right angles to the edges of 

 the plates. Such folding is well seen in the geuus Vasocrinus, in Gisso- 

 crinus goniodactylus, and in the ornate individuals of Marsupites testu- 

 dinarivs where it is often accompanied by smaller parallel ridges. 

 Whether it be of any morphological importance we need not now inquire ; 



