i895. RESULTS OF ^'CHALLENGER" EXPEDITION. 43 



one genus and three species, and the " Challenger " added two genera 

 and twenty species, which, with a species from the " Blake," brought 

 the number up to the six genera and twenty-eight species discussed in 

 P. H. Carpenter's Report. 



If present seas compare unfavourably with those of Palaeozoic 

 periods in the number of species of Stalked Crinoids, they at least 

 rival them when the Unstalked Crinoids are taken into account. 

 Carpenter's second volume considers six genera collected by the 

 " Challenger," of which two were new, and 180 species, of which no, 

 including 88 new forms, were dredged by the " Challenger," A less 

 conscientious or less learned worker would have vastly increased the 

 number ; Carpenter himself at first estimated them as over 400. 



The new genera discovered were of profound interest. Among 

 stalked forms: Bathycrimis (PI. viii.. Fig. i), with fused basals and 

 remarkable arrangement of axial nerves; Hyocriims (PI. viii., Fig. 2), 

 singularly archaic in its lofty basals and massive orals, and somewhat 

 resembling certain Silurian crinoids in its lengthy pinnules ; Metacrinus, 

 with more brachials below the first main axillary than had been seen 

 for many a geological period. Among unstalked forms : Promachocrinus 

 (PI. viii.. Fig. 3) with twice as many radials as we were used to ; 

 Thaumatocnnus (PI. viii., Fig. 4), that wonderful creature from the 



Southern Ocean, reminiscent of the Taxo- 

 crinidae in its anal process {a a), of the Rhodo- 

 crinidae in its interradials (i), and of the Larvi- 

 formia in its orals, yet all the time with a 

 centrodorsal (cd) like any Antedon.^ 



In distribution we note how the widest 

 range, both geographical and bathymetrical, is 

 possessed by those forms that we have reason 

 to regard as geologically older or morpho- 

 logically simpler, though so far as present 

 knowledge goes, it does not appear that a wide 

 range in depth is always correlated with wide 

 horizontal distribution. 



Such increase to our knowledge would 

 have resulted from the voyage of the " Chal- 

 lenger," to whomsoever the collections had been 

 entrusted. But the studies of Carpenter 

 revealed to us far more. It was not in the 

 region of histology that much was gleaned, 

 for the specimens had unfortunately not been preserved to that end, 

 and had moreover been many years in spirit before they reached 



whi^^ 



Fig. 6. — Myzostoma quadri- 

 filum : parasitic on Ante- 

 don bidentata ; from ven- 

 tral surface ; x 4 diam. 



1 Mention may here be made of the parasites of the crinoids, Myzostoma and 

 Stelecliopus, which have induced the formation of plated swellings on the exterior of 

 recent and fossil forms. Von Graff, by his study of the " Challenger " specimens, 

 threw great light on the structure and affinities of this obscure group, which the 

 discovery of a setiferous larva now causes us to place among the Chaetopoda. (Fig. 6.) 



