MONOGKAPH OF THE EXISTING CRINOIDS. 121 



In the following year Prof. Hubert Ludwig, whose four papers published in 

 1876 had constituted a notable contribution to the study of the anatomy of the 

 comatulids, and of Rhizocrinus, completed liis investigations and laid before the 

 scientific world an exhaustive account of the whole subject, in which many points 

 over which there had for years been controversy were permanently settled. At 

 the same time P. H. Carpenter published a preliminary^ notice of liis important mono- 

 graph on the genus Actinometra (now known as the family Comasteridse), which 

 was published in its final form two years later. 



In 1878 P. H. Carpenter published a contribution to the knowledge of the oral 

 and apical systems of the echinoderms, a line of work which subsequently called 

 forth many more or less similar papers from his pen. In 1879 there appeared 

 another memoir on the same subject, a short account of the nervous system, a 

 discussion of the terminology of the parts of the crinoid calyx, and the above men- 

 tioned masterly and veiy comprehensive treatise on the genus Actinometra all by 

 the same author. 



In 1880, 1881 and 1882 Carpenter pubhshed a number of papers dealing with 

 various points in the anatomy, especially the minute anatomy, of recent forms, 

 with the homologies of the apical system, the comparative structure of recent and 

 fossil comatulids and of the endocyclic and exocyclic recent species, and with various 

 other points. In 1881 he amiounced the interestmg discover}' of true basals in a 

 recent type of comatuhd, which he therefore considered worthy of generic rank, and 

 called Atelecrinus. 



In 1883 he discussed the anatomical relations of the vascular sj'stem of the 

 echinoderms, supporting the conclusions reached by Ludwig and by his father, and 

 dissenting from those attained by Perrier, Kcehlcr and Apostolides. 



Early in 1884 his memoir on the remarkable Thaumaiocrinus (recently found 

 to be but the young of a form described under another name) exhibiting numerous 

 primitive characters, appeared. In the same year he published a discussion of 

 certain pomts in the anatomy of larval comatulids, and an account of the apical 

 plates of the ophiuroids, while his father, as well as Prof. A. M. Marshall and Dr. 

 Carl F. Jikeli furnished important contributions to the study of the nervous sj-stem, 

 especially from the physiological point of view, all three ha\'ing conducted experi- 

 ments upon the living animals, W. B. Carpenter on Antedon bifida, and Marshall 

 and Jikeli on A. mediterranea. But the year 1884 is chiefly notable for the appear- 

 ance of the Ofiallenger monograph on the stalked ciinoids, by P. II. Carpenter. In 

 this monograph all phases of the subject are treated, and the comatuhds are 

 exhaustively considered in regard to their structure, morphology and homologies, m 

 the body of the work, and especially in the several appendices. 



The year 188.5 witnessed the appearance of part three of Wachsmuth and 

 Springer's revision of the so-called Palseocrinoidea, in which the recent crinoids 

 come in for a large amount of instructive discussion. In this year Carjienter con- 

 tributed four papers, all dealing more or less extensively with the niorphologs' of 

 the recent crinoids, and Perrier three, dealing mainly with the organization of the 

 young. 



79140°— Bull. 82—15 9 



