6 INTRODUCTION. 



system, as a modern representative of Apiocrinus. ^ A more careful exami- 

 nation has sliown many points of difference, and I propose to establish a 

 new o-enus for this Crinoid, one of the most interesting brought to light 

 by any of the deep-sea dredging expeditions. 



It is most closely allied to a large group of Mesozoic Crinoids, and helps 

 us to understand more clearly many ^Doints in their morphology ■which 

 were left somewhat doubtful from our imperfect knowledge of the Jurassic 

 Apiocrinidaj. In a preliminary notice of this Crinoid,* I proposed for it 

 the name of Calamocrinus Diomedaj.f 



The first genus of the family (Encrinus) makes its appearance in the 

 Muschelkalk, and is specially characteristic of that formation. The Apio- 

 crinidaj first appear in the inferior Oolite (Millericrinus). In the upper 

 beds of the Great Oolite we find Eugeniacrinus and Apiocrinus, the latter 

 extending to the Coral Rag. 



In the Oxford Clay and Coral Rag, Guettardicrinus and Millericrinus 

 abound, together with Apiocrinus. In these beds Millericrinus attains its 

 maximum development, but it also disappears entirely, as well as the other 

 Apiocrinidas, in the upper beds of the Oolite. They have not been found 

 in tlie lower Cretaceou.s, but again make their appearance in the White 

 Chalk (Bourgueticrinus). They have not as yet been discovered in the 

 Tertiary, but thej^, or their allies, have been brought to light in the deep 

 seas of the present day (Rhizocrinus and Calamocrinus). 



It is interesting, in view of the discovery of so many genera of Crinoids 

 by the recent deep-sea explorations, to recall the speculations of D'Orbignj^t 

 on their probable existence in our seas. He says : — 



" Tons ces genres et ces especes qui ont peuple les mers a des epoques 

 reculees, parurent longtemps n'avoir pas survecu aux epoques gtologiques ; 

 an moins, en scrutant les annales de la science etait-on tente de le croire ; 

 mais je crois aujourd'hui qu'il en existe encore de vivantes. . . . 



" M. Saint-Cyr Hotessier ... a bien voulu me communiquer des ^chantil- 

 lons de breches rccentes (de la Guadeloupe). . . . Comme les breches ou 

 se rencontrent ces restes de Crino'.'des (Bourgueticrinus Hotessieri, D'Orb.) 

 se ferment encore journellement, et qu'elles contiennent seulement des es- 

 peces vivantes aujourd'hui, on doit croire que ce Crinoide important existe 



* Neues .lahrb. f. Mineral., 1890, I. 



t Bull. Mus. Comp. ZoiJl., Vol. XX. No. 6, December. 1890. 



X Histoire Naturelle generale et particuliere de.s Crinoides vivants et fossiles, comprenant la des- 

 cription zQologique et geologique de ces auimaux, par Alcide D'Orbigny. 3* Livraison, Paris, 1840. 



