302 



PHYLUM ECHINODERMATA. 



Fam. Hyoerinidae. Calyx high, composed of 3 basals, sometimes 

 fused, and 5 radials nearly equal in length. Each radial bears a small 

 undivided arm, brachials united by syzygy 

 A into groups of 2 or 3, only the distal of which 



bear pinnules. The proximal pinnules are 

 longer than the distal and reach to the end of 

 the arms. Calyx cover plated, with 5 large 

 orals round the mouth, with covering plates. 

 Water pores perforating the orals as in Rhizo- 

 crinus, but more numerous. Hyocrinus W. 

 Thorns. (Fig. 209), 1,600 to 1,900 fms., Atlantic. 

 By its calyx Hyocrinus is related to the Larvi- 

 formia, and by its pinnules which all terminate 

 at about the same level, the proximal being 



FIG. 209.Hy3crinus bethellianus W. Thorns, (from Zittel, after W. Thorns.). A side-view, 

 twice nat. size. B calyx-cover magnified ; am ambulacral grooves of arms, c axial canal 

 of arm joints, an anus, m mouth, o oral plates. 



longer than the distal, to Cyathocrinus, where, however, we have to do 

 with branching arms, not pinnules. Gephyrocrinus * Koehler and Bather, 

 1786 metres, Canaries. 



Fam. Holopidae. Calyx cup-shaped, containing 

 all the viscera and fixed by its base to the sub- 

 stratum ; no stalk. The calyx shows no distinct 

 sutures dividing it into areas, so that it is impos- 

 sible to say of what plates it is composed, though 

 there are slight indications of a composition of 

 radials at the upper end of cup. 10 massive arms 

 closely rolled in upon the calyx cover (Fig. 210). 

 Calyx cover with 5 large orals and marginal plates. 

 Anus not observed. There is one primibrachial 

 (if we may so call it) articulated to the edge of 

 the cup and 10 arms-branches. Pinnules present. 

 Holopus d'Orb. Deep water, Caribbean Sea. 



The first s P ecimen found in 1857 was tetrara- 

 ing the 10 arms bent diate ; more specimens subsequently came to 



over the calyx cover hand, and it was eventually found bv the Blake. 



(after Agassiz from De- _,. ' T 



lage and HeYouard). The Blake specimens were dredged at 100 fms. 



* Mem. Soc. Zool. France, 15, 1902, p. 68. 



