REPORT ON THE CRINOIDEA. 37 



IV.— THE GEOLOGICAL HISTORY OF THE COMATULtE. 1 



So far as our present information goes the family Coniatulidse first appeared in the 

 time of the Middle Lias and is therefore of somewhat less antiquity than the Penta- 

 crinidae which date back to the Trias. Comatulee were fairly abundant all through the 

 Jurassic and Cretaceous epochs and were especially so at certain periods, that of the 

 Corallian in Germany and Switzerland, for instance. 



The geographical distribution of recent Comatulse is far more extensive than that of 

 their predecessors. The distribution of the former is practically world-wide ; but so far 

 as is yet known, with the exception of an Antedon from Algeria and another from Syria, 

 no fossil Comatulse have been discovered out of Europe, not even in the Indian 

 Tertiaries, which contain so many Echinoderm remains. None are known in America, 

 though stem-joints of the remarkable Pentacrinus asteriscus are very common at certain 

 horizons of the Jura-Trias over wide areas of the western territories; and this shows 

 that the conditions of that long-distant age were not altogether unfavourable to the 

 development of Crinoid life. On the other hand, the Middle Lias of France contains 

 two species of Antedon, the oldest yet known ; and the genus occurs, together with 

 Actinometra, in the lower Oolites of both France and England ; while if Bourgueticrinus 

 ooliticus, M'Coy, is a Thiolliericrinus, as supposed by de Loriol, it is the earliest known 

 species of this very singular genus. 



Both Antedon and Actinometra, especially the former, are well represented in the 

 Corallian of the Jura, and there are several species of Antedon in the Neocomian of the 

 continent, together with a few in Britain. The Gault of Folkestone has yielded typical 

 forms of both genera, and there are several Cretaceous species of Antedon scattered 

 through Europe, the formerly obscure Glenotremitcs paradoxus being the best known. 

 We are only acquainted with one Eocene Comatida; though three species occur in the 

 French Miocene, and there are others in the Pliocene both of England and of Italy. 



In the majority of cases only the centro-dorsal is preserved, though it is not 

 uncommon for the radials to remain attached to it. But individuals with any arm- 

 joints preserved beyond the calyx-radials are decidedly rare ; and in this respect the 

 Comatulse differ widely from the Pentacriims-type, isolated calyces of which are not 

 often met with, though the arms are frequently extraordinarily well preserved. 



One singular instance of the retention of the arms or arm-bases is afforded by 

 Eudiocrinus hyselyi. 2 But for this fact the existence of Eudiocrinus in the fossil state 



x I am indebted to the kindness of M. P. de Loriol for much information respecting the fossil Comatulidae of 

 France and Switzerland, some of it being as yet unpublished. 



2 See de Loriol, Monographic des Crinoides fossiles de la Suisse, Geneva, 1877-79, pi. xxi. fig. \4. 



