HISTORICAL REVIEW. 11 



G. M. Bowers, Dr. D. S. Jordan, and Dr. C. H. Gilbert I am indebted for a 

 portion of the material, to certain data relating to a few of the species and for 

 many courtesies while on board the "Albatross." I am likewise under deep 

 obligation to Drs. E. J. Nolan and H. A. Pilsbry for the use of the magnificent 

 library of the Philadelphia Academy of Sciences, and for several suggestions of 

 a most helpful character. To Dr. W. K. Fisher I am indebted for the identi- 

 fication of the alcyonarian hosts and for a specimen of Chaciodcrma hmmiiensis. 

 I also wish to express my gratitude to my assistants. Miss R. M. Higlcy, and 

 Mr. F. W. Weymouth who have greatly lessened the burden necessarily involved 

 in such a study as this. And finally my indebtedness to the late Mr. Alexander 

 Agassiz is very great; in every way possible he helped the work along. 



HISTORICAL REVIEW. 



The first known reference to any species of Solenogastre occurs in the 

 works of Loven, who in 1844 briefly described as a gephyrean worm Chaeto- 

 derma nitidulum. During the next thirty years a number of systematists 

 adopted this scheme of classification though there was some difference of opinion 

 concerning the exact position of the species within the group. Diesing ('59), 

 Keferstein ('65), Quatrefages ('65), and Baird ('68) allied it to Sipunculus or 

 Priapulus; Theel ('75) created for it a new family (Chaetodermidae), while 

 M. Sars ('69) placed it among the gephyreans without any comment. Dalyell 

 ('53) in "The Powers of the Creator" gives under the name Vermiculus crassus 

 an abbreviated description and one figure of an undoubted Chaetoderma, ac- 

 cording to Koren and Daniellssen ('77) C. dahjelli, but the description is much 

 too indefinite to make the determination certain. 



During this time M. Sars discovered another species of Solenogastre, be- 

 longing to a new genus and ultimately to a new family, which he placed ('69) 

 among the MoUusca without any comment whatever, merely giving it the 

 name Solenopus nitidulus. Some years later Tullberg ('75) described what is 

 considered to be the same sjjecies under the name Ncomenia carinata. This 

 last named author's investigations mark a distinct advance in our knowledge of 

 these forms, since they are concerned not only with the study of the external char- 

 acters l)ut with the internal organization as well. In certain respects, especially 

 in the treatment of the urogenital system, the work is seriously at fault, but never- 

 theless it was thoroughgoing enough to lead Tullberg to conclude that, while 

 the species is vermian in what he considered to be probably the most important 

 characters, it is on the other hand decidedly similar to certain of the Mollusca. 



