48 INVERTEBRATE ANIMALS. 



seldom been brought to light, and was long regarded 

 as a solitary relic of the vast Crinoid population of 

 the ancient oceans. Deep- sea dredging has recently 

 afforded examples of allied forms. Pentacrinus Wyville- 

 Thomsoni was taken at a depth of 1,095 fathoms, 

 E. Atlantic, and Bathycrinus gracilis at 2,435 fathoms. 

 Estimated number of species : recent, 10 ; fossil, 6. 

 Lias. 



The collection is fortunate in possessing one fine 

 specimen of P. Mulleri and two of P. Wyville- 

 Thomsoni. Whilst inspecting them, Dr. Car- 

 penter, who described and named the latter 

 species, remarked to the writer that, in conse- 

 quence of a structural peculiarity, the stem of 

 a Pentacrinite never snapped asunder except at 

 a joint close below one of the whorls of arms 

 - which at intervals of about three inches radiate 

 from the stem. If, therefore, the stem of a 

 living Pentacrinite broke, a whorl was thereby 

 brought in close and even contact with the 

 sea-bottom, to which the arms could cling and 

 again support the animal in an erect position. 



Group 135.— Family COMATULID^. Feather-stars. 

 Although the adult Feather-stars move freely from place 

 to place, in their early condition they are attached by 

 the centre to a fixed stem, in which stage they so 

 much resemble the species of the preceding group, that 

 the larval state of Comatula rosacea received the name of 

 Pentacrinus Europceus. Estimated number of species : 

 recent, 35 ; British, 3 ; fossil, 20. 



