432 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



discovery of a stalked crinoid in European waters aroused very considerable 

 interest and was widely noticed. Subsequent study of these small creatures showed 

 that instead of being adult pentacrinites they are in reality only the young of 

 the common comatulid of the Irish coasts, Antedon bifida — a discovery which 

 Thompson announced in 1835. 



Tliompson found that the ova are developed in conceptacles formed by the 

 thickening of the membranous expansion within each of the first 15 or 20 pairs 

 of pinnules beyond the oral pair, and that the ova make their exit through a round 

 hole in the fascial side of each conceptaculum, " still, however, adhering together 

 in a roundish cluster of about a hundred each." 



In the same year Dujardin also noticed the development of ova in the pinnules 

 and their escape through apertures formed in the integument in Antedon viedi- 

 tei'ranea at Toulon. 



In spite of the seemingly conclusive accounts of Thompson and Dujardin, 

 Edward Forbes in 1841 stated that spermatozoa only are found in the swollen 

 pinnules and mistook the sacculi for ovaries. From original observations made 

 in Dublin Bay he confirmed the identity of Pentacrinui< europceus with Antedon 

 bifida, in regard to which Dujardin was somewhat doubtful. 



The existence of a free-swimming larval stage in the comatulids had not as 

 yet been demonstrated. In 1851 Wilhelm Busch, a pupil of Johannes Miiller, 

 published an account of such a larva which he had found during a visit to England 

 and Scotland, but he did not succeed in tracing its development. Incidentally the 

 larva he describes and figures, which resembles to a striking degree a holothurian 

 pupa, is abnormal, representing a rather frequent type of precocious development. 



In 1863 Professor Allman published a memoir upon a prebrachial stage in the 

 development of the stalked larva of Antedon bifida, his material consisting of a 

 single specimen which he had obtained on the coast of South Devon. 



Two years later Sir C. Wyville Thomson published an excellent account of the 

 early stages of Antedon bifida, which was supplemented in the following year by 

 the masterly Avork of Dr. W. B. Carpenter upon the later developmental stages of 

 the same species. 



In 1873 Prof. Edmond Perrier published a short paper which marks his entry 

 into a field where later he was to achieve so much distinction, and in 1876 Giitte 

 published the results of his studies on the comparative embryology of Antedon 

 mediferranea. In the next few years Professors Hubert Ludwig and Elias ^letsch- 

 nikoff made notable contributions to the developmental hi.story of the same species, 

 though from the anatomical rather than from the embryological standpoint. 



In the eighties original investigation and philosophical consideration of the 

 development of Antedon were undertaken with renewed vigor, the former because 

 the many new refinements of technique had made more accurate work possible, 

 the latter as a result of the wonderful wealth of fossil forms recently discovered. 

 During this decade Perrier made numerous original contributions to the subject, 

 culminating in his exhaustive and elaborate monographic survey of the field based 

 mainly upon Antedon moroccana and A. bifida, which was published in 1886. 

 Professor Jules Barrois, in addition to some short papers, published an excellent 



