MORPHOLOGICAL PART. 77 



calycine tubes, and the original pinnules into alternately arranged pinnule- 

 bearing arms. This shows that the second part of Bather's terminology 

 cannot be carried out practically, and we see no good reason why the former 

 terms could not be used for all Crinoids, pinnulate or non-pinnulate. 



The costals of the Camerata, as a rule, consist of two plates to the ray ; 

 exceptionally of one or three. Flatycrimis has generally but one ; but two 

 of its earlier species have two, and it is quite probable that the genus origi- 

 nally had two costals, wdiich later on w^ere united into one. This seems to 

 be confirmed by the fact that some of the species have transverse grooves at 

 the dorsal face of the plates, and that in multibrachiate species, the distichals 

 and succeeding orders are composed of two pieces. Stereocrinus also has but 

 one costal, which has the proportions of the combined first and second plates 

 of Dolatocriniis, with which it has very close affinities. The same structure is 

 found in Anthemocrimis and Hadrocriniis, Dichocriniis has two costals, which 

 form a syzygy, the epizygal supporting an arm. The allied Talarocriniis and 

 Pterotocrinus, however, have but one. In Batocriniis, and in most of the Bato- 

 crinites, the first costal is very short, and is frequently anchylosed with the 

 second in one or more of the rays. Three costals occur among Camerate 

 Crinoids only in Reteocriniis stellaris, and in Hall's imperfectly known 

 Schizocrimts, 



Among the Articulata the number of costals is more variable, and often 

 differs among the rays of the same individual. Forhesiocrinus Agasski^^ may 

 have two or three costals in all its rays, or four only in one or two of them. 

 Calpiocrinus and Mespilocriniis have two, Icliihyocrimm and Taxocriniis two to 

 three, and Anisocrinus but one ; while Onychocrinus has from three to six. 



The number of costals is still more variable in certain groups of the 

 Fistulata, in some of which such irregularity is the rule. This is the case in 

 Cyathocrinus and Parisocrinus^ in which one ray may have two, the adjoining 

 one three, and the next perhaps five or six. Codiacrinus has two to three, 

 Atelestocrimis froui two to six. Less variable among the rays, but still numer- 



* We are of the opinion that Forhesiocrinus nobilis, de Koninck's type of the genus, is generically iden- 

 tical with OnycJiocrinus Lyon. We recently obtained from Tournai, Belgium, a fine specimen with arms, 

 which clearly shows that it has a small anal tube resting upon the first anal plate. The rays are free above 

 the first costal, and are extremely heavy to the fourth distichal, wlience they branch off into numerous small, 

 curving armlets, exactly as in Onijchocrinus exsculptus Lyon. De Koninck stated that in liis species the 

 plates of the anal side, which were imperfectly shown in the specimens, were probably more numerous than 

 those of the other sides, whereas the fact is the opposite ; and this statement, no doubt, led Hall and others 

 to refer Forhesiocrinus Agassizi and allied forms, in which that actually is the case, to de Koninck's genus. 

 If, therefore, de Koninck's type is that of Onychocrinus, the latter name may have to be abandoned, and 

 a new generic name proposed for such forms as F. Agassizi. 



