REPORT ON THE CRINOIDEA. 297 



Tn the year 187G a Inrge Pentacrinus colony was discovered at Sennecey-le-Grand. 

 Numerous very perfect individuals were obtained and carefully described by de Loriol.' 

 He found a verticil of cirri on every joint, and described their faces as follows : — 

 " La surface articulaire est plane ; les petales de la rosette articulaire sont fort 

 etroits, et ont I'apparence de cinq petites rigoles aboutissant aux cinq angles du 

 pentagone et limitdes par deux petits bourrelets paralleles, plus eiev^s sur I'une des 

 faces de 1' article que sur I'autre, et converts de tres fines crenelures." The figure which 

 he gives (pi. ii. fig. 10) shows the complete correspondence of these joints with those 

 of the Liassic Extracrinus ; and he found this correspondence also in the other characters 

 of the type. The radials extend slightly downwards over the top stem-joints, and the 

 characters of the arm-divisions are almost exactly as in Extracrinus, except that the 

 main arms and the armlets which they bear are more equal in size than in the typical 

 species. 



De Loriol identified this species with Pentacrimis dargniesi of Terquem and Jourdy, 

 though he considered it as belonging to the same group as Extracnnus hriareus ; but 

 he hesitated to adopt Austin's genus, and he subsequently stated that there was no reason 

 to do so.* 



He also pointed out that the characters of the stem-joints and cirri of Quenstedt's 

 two species Pentacrimts hriareus zollerianus and Pentacrinus hriareus achalmianus, both 

 from the Brown Jura (Inferior Oolite), indicate their affinity to this grouj). In the same 

 memoir he described and figured some other stem-joints presenting all the Extracrinus- 

 characters from the same formation (Bajocien) of Langres, and he subsequently found 

 both these types at corresponding horizons in Switzerland. He referred at the same time 

 to the Pentacrinus nodotianus, d'Orbigny, whicli was descril^ed l^y its founder as being 

 " voisine du Pentacrinus hriareus." Very similar stem-joints, each bearing five 

 cirri, and having crenulated linear petals, occur in the Coralline Oolite of various 

 parts of Switzerland, and are described as Pentacrinus buchsgauensis by de Loriol, 

 who notes their resemblance to those of Pentacrinus hriareus as a point of special 

 interest.' 



We may therefore, I think, consider it certain that Extracrinus extends up above 

 the Lias into the Lower Jurassic rocks of the Continent, and the same is undoubtedly the 

 case in England. The Great Oolite of Minchinhampton contains stem-joints ■s\'ith the 

 same linear, crenulated petals as those of the Liassic Extracrinus hriareus ; while similar 

 joints, together with arm-fragments showing the characteristic inequality of division, 

 abound in the Forest Marble at Malmesbury. 



To the genus Extracrinus I would also refer the Pentacrinus asteriscus from tlie 



' Notice sur le Pentacrinus de Sennecey-le-Granil, p. 7. Both in this work anrl in the Swiss Criuoicls this type 

 is called Pentacrinua dargniesi by de Loriol. But the plates are lettered Pentacrinus chahasi, P. de Loriol. 

 2 Swiss Crinoids, p. 116. 3 xiUfi^ pp 153^ 154, 



(ZOOL. CHALL. EXP. — PAIIT XXXII. — 1884.) Ti 38 



