296 PROCEEDINGS OF THE ACADEMY OF [1885. 



well developed, being either rudimentary or absent. Basals five, 

 exceptionally three. Radials perforated, and generally united to 

 succeeding plates by a muscular articulation. Rays simple or 

 dividing ; the lower arm joints frequently connected laterally by 

 perisome. The first axillary plate generally the second joint 

 after the first radial ; arms uniserial. Ventral surface completely 

 occupied by actinal structures, either simply membranous or 

 paved with irregular plates ; traversed by the ambulacra, which 

 have open food grooves. Orals five ; always represented in the 

 larva, but frequently resorbed in the adult ; at first in lateral 

 contact, but afterwards separating so as to open out the tentacular 

 vestibule, and expose the mouth. 



Classification. 



The " Stalked " Echinoderms, by which we understand the 

 Crinoidea in their widest sense, have been regarded by some 

 writers as constituting an independent class, by others as an 

 " order " of the class Echinodermata. The latter view, which has 

 been adopted by most of the later European systeniatists, was 

 somewhat modified in the classification of Dr. P. H. Carpenter, 

 who ranks the Stalked Echinoderms under the name " Pelma- 

 tozoa " as a " branch " of the " phylum " Echinodermata, and he 

 makes the Crinoidea — sensu str. — and the Cystidea and Blas- 

 toidea, full classes, of equal rank with the Holothurians, Echi- 

 noids, Asteroids and Ophiurids. 



The name Pelmatozoa, as stated by Carpenter (Chall Rep., p. 

 193), was introduced by Leuckart in an essay published in 1848, 

 and more fully discussed in 1865, in his " B'ericht iiber die wis- 

 senschaftlichen Leistungen in der Xaturgeschichte der niederen 

 Thiere." In the latter paper he subdivides the Echinodermata 

 into three groups : the Pelmatozoa, to include the Stalked Echi- 

 noderms, i. e., Crinoidea in the broadest sense; the Sc}'toder- 

 mata, to embrace the Holothurians ; and the Echinozoa, under 

 which he placed the Urchins, Starfishes and Ophiurans. 



That the Stalked Echinoderms and Holothurians are more 

 distinct from each other, and from the three groups for which 

 Leuckart proposed the name Echinozoa, than these are among 

 themselves, cannot be denied, but it is questionable whether it is 

 necessary or even desirable to express this in the classification, 

 any further than by placing in juxtaposition the nearest allied 

 groups. To.> many subdivisions encumber the classification, and 



