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. Péu/yerinus 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, which later on were 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. Sfereocrinus also has but 
one costal, which has the proportions of the combined first and second plates 
of Dolatocrinus, with which it has very close affinities. The same structure is 
found in Anthemocrinus and Hadrocrinus. Dichocrinus has two costals, which 
form a syzygy, the epizygal supporting an arm. The allied Tularocrinus and 
Pterotocrinus, however, have but one. In Batocrinus, 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 Refeoerinus stellaris, and in Hall’s imperfectly known 
Schizocrinus. 
Among the Articulata the number of costals is more variable, and often 
differs among the rays of the same individual. Forbesiocrinus Agassizi* may 
have two or three costals in all its rays, or four only in one or two of them. 
Calpiocrinus and Mesyilocrinus have two, Ichthyocrinus and Taxoerinus 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, 
Alelestocrinus {rom two to six. Less variable among the rays, but still numer- 
* We are of the opinion that Porbesiocrinus nobilis, de Koninck’s type of the genus, is generically iden- 
tical with Onychocrinus 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, whence they branch off into numerous small, 
curving armlets, exactly as in Onychocrinus exsculptus Lyon. De Koninck stated that in his 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 Forbesiocrinus Agassizi and allied forms, in which that actually is the case, to de Koninck’s genus. 
Tf, therefore, de Koninck’s type is that of Onychoerinus, the latter name may have to be abandoned, and 
a new generic name proposed for such forms as /. Agassizt. 
