22 6 NATURAL HISTORY BULLETIN. 



expedition. Two other species, Porponia elongata and P. 

 robusta, were also doubtfully referred to it, and later, in a sup- 

 plementary report ('88), a third genus Ilyanthopsis was added. 

 The distinguishing characteristics of the family as given by 

 Hertwig were the "slightly developed muscular system; long, 

 slightly contractile tentacles, without any circular muscles 

 (tentacles consequently non-retractile); reproductive organs 

 present on all the septa; numerous complete septa; accessor} 7 

 tentacles wanting." It is to be noted, however, that none of 

 the species referred to the family by Hertwig were suitably 

 preserved for an exhaustive study, and some uncertainty exists 

 as to the structure and arrangement of the mesenteries in all 

 of them. Furthermore, if Porponia elongata is to be retained 

 in the family it will be necessary to modify the definition as 

 regards the distribution of the reproductive organs on all the 

 mesenteries, since in the species mentioned imperfect non- 

 gonophoric mesenteries occur. 



In the collection made by the United States Fish Commis- 

 sion Steamer Albatross, I found a form which in my report 

 ('93) I named Halcurias -pilatns, referring it, chiefly on account 

 of the arrangement of its mesenteries, to the family Halcam- 

 pidae. Carlgren ('93) has, however, shown that in two typical 

 species of the genus Halcampa the sphincter muscle is meso- 

 gloeal and this added to the fact that Halcurias possesses an 

 adherent base makes it advisable to remove it from the Hal- 

 campidag. It seems to me that by modifying slightly the 

 definition of the family Antheomorphidas a place may be found 

 for it in that group, in fact I was inclined at first to associate 

 it with Porponia and was only deterred from doing so by the 

 simplicity of the arrangement of its mesenteries. I would 

 suggest as a definition of the Antheomorphidas the following: 



Actininag with an adherent base; column smooth; tentacles 

 simple, long or moderately so, conical or digitiform : sphincter 

 muscle and acrorhagi wanting; no cinclides or acontia; no 

 conchula; mesenteries all or nearly all perfect, all (?) the per- 

 fect ones gonophoric. 



As Hertwig has pointed out the chief difference between 



